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This paper presents the results of physical modelling of the process of multi-pass rolling of a wire rod with controlled, multi-stage cooling. The main goal of this study was to verify the possibility of using a torsion plastometer, which allows conducting tests on multi-sequence torsion, tensile, compression and in the so-called complex strain state to physically replicate the actual technological process. The advantage of the research methodology proposed in this paper in relation to work published so far, is its ability to replicate the entire deformation cycle while precisely preserving the temperature of the deformed material during individual stages of the reproduced technological process and its ability to quickly and accurately determine selected mechanical properties during a static tensile test. Changes in the most important parameters of the process (strain, strain rate, temperature, and yield stress) were analyzed for each variant. After physical modelling, the material was subjected to metallographic and hardness tests. Then, on the basis of mathematical models and using measurements of the average grain size, chemical composition, and hardness, the yield strength, ultimate tensile strength, and plasticity reserve were determined. The scope of the tests also included determining selected mechanical properties during a static tensile test. The obtained results were verified by comparing to results obtained under industrial conditions. The best variant was a variant consisting of physically replicating the rolling process in a bar rolling mill as multi-sequence non-free torsion; the rolling process in an NTM block (no twist mill) as non-free continuous torsion, with the total strain equal to the actual strain occurring at this stage of the technological process; and the rolling process in an RSM block (reducing and sizing mill) as tension, while maintaining the total strain value in this block. The differences between the most important mechanical parameters determined during a static tensile test of a wire rod under industrial conditions and the material after physical modelling were 1.5% for yield strength, approximately 6.1% for ultimate tensile strength, and approximately 4.1% for the relative reduction of the area in the fracture and plasticity reserve. [ABSTRACT FROM AUTHOR]

Hardwoods commonly have high mechanical properties, which makes them interesting for structural use, but softwoods dominate the structural timber market in Europe. Tensile strength classes are recommended for engineered wood products. However, current European standards do not provide tensile strength classes for hardwoods and the declaration of tensile properties from machine grading in the industry is not yet possible. The present paper aims to contribute to the revision of European standards through the technical group CEN/TC124/WG2/TG2: Tensile strength classes for hardwoods, of the European Standardisation Committee. An experimental campaign which involved machine grading and tensile testing of over 569 boards of Southern blue gum (Eucalyptus globulus Labill.) from Spain and Portugal was made. Six new tensile strength classes were defined, from ET24 (ft,0,k = 24 N/mm2, Et,0,m = 18 kN/mm2 and ρk = 590 kg/m3) to ET42 (ft,0,k = 42 N/mm2, Et,0,m = 23 kN/mm2 and ρk = 640 kg/m3). Machine grading made possible the definition of six strength class combinations. Four combinations resulted in 40% of the sample being assigned to the higher strength class, with low percentages of rejection (varying between 1% and 14%). This demonstrates the high mechanical properties of the species and the performance improvement of machine grading with respect to current visual grading. [ABSTRACT FROM AUTHOR]

The present paper focuses on the configuration possibilities of post -processor influencing mechanical properties of a given test sample produced by the FDM printer from different materials. The research consists of assessing the composite material configurations through a static tensile test conducted on 80 samples produced. The samples were produced based on ISO 527-2 standard, type 1A, with a horizontal position and a layer height of 0.2 mm. The individual samples consisted of four basic groups of materials—the pure Polylactic acid (PLA) plastic (reference sample), and three composite samples with admixtures—PLA matrix with a copper admixture, PLA matrix with an iron admixture, and PLA matrix with a steel admixture. The static tensile test was conducted at a test speed of 5 mm/min. During the research, reference samples (pure PLA) were assessed in five orientations. Samples made of the PLA composite materials with admixtures were manufactured, tested, and evaluated only in the 0° orientation. The paper concludes by comparing the results of measurement with the original material, free from additives, and with the researched influence of the orientation of the prints on the resulting mechanical properties of shear samples and their surface structure. In the conducted experiments, the lowest tensile strength has been demonstrated in test samples the orbital transitions and the upper surface layers of which were parallel to the infill. [ABSTRACT FROM AUTHOR]

In this present paper, the mechanical properties of σ-phase and its effect on the mechanical properties of 304H austenitic stainless steel after servicing for about 8 years at 680–720 °C were studied by nano-indentation test, uniaxial tensile test, and impact test. The results showed that the nano-hardness (H), Young's modulus (E), strain hardening exponent (n), and yield strength (σy) of σ-phase were 14.95 GPa, 263 GPa, 0.78, and 2.42 GPa, respectively. The presence of σ-phase increased the hardness, yield strength, and tensile strength, but greatly reduced the elongation and impact toughness of the material. [ABSTRACT FROM AUTHOR]

In this paper, the roles of the welding process on the heterogeneous microstructure and mechanical properties of Q345R welded joints were analyzed by a series of tests, including the preparation of welded joints with different welding processes, optical microscope observation, uniaxial tensile tests, and hardness and impact measurements. The experimental results show that with the increase in welding heat input, the content of pre-eutectoid ferrite and the size of the Weidner structure increased, while the hardness and the impact absorption energy of the weld zone decreased gradually. With the increase in heat input, the volume proportion of eutectoid ferrite in the weld increased from 9.90% to 18.78%; the volume proportion of acicular ferrite decreased from 85.10% to 76.21%. With the decrease in heat input, the volume proportion of eutectoid ferrite decreased from 10.58% to 1.45%, and the volume proportion of acicular ferrite increased from 84.21% to 92.74%. Under the influence of the second welding heat, the first weld zone, the fusion zone and part of the heat-affected zone were re-austenitizing, and the distribution of ferrite and pearlite was more uniform. The hardness value of the former weld was lower than that of the second weld, and the distribution was more uniform. The maximum hardness value of the second weld zone and its corresponding heat-affected zone increased with the increase in depth. The distribution of the yield strength and the tensile strength of welded joints was similar to that of hardness. [ABSTRACT FROM AUTHOR]

Titanium alloy extruded profiles with complex cross-section are usually used to manufacture special-shaped structural parts in the aviation industry. In this paper, a Ti-6Al-4 V profile with asymmetric Y shape was manufactured by a direct extrusion process. A comparative study was conducted at the different lubrication conditions, in which the different process deformation mechanisms, resulting microstructures, and mechanical properties of profiles have been investigated by finite element simulation and a series of experiments, i.e., scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). It was revealed that the metal flow is blocked at the narrow die orifice due to the deterioration of lubrication, resulting in the continuous shrinkage defect. The metal deformation coordination mechanism becomes gradually significant due to poor friction contact, which promotes the internal stress in the cross-sectional center to transfer outward to balance the friction at the edge of the orifice, resulting in the reduction of the effective strain in the center. The heat generated by friction weakens the heat exchange behavior between the metal and the die, which helps the profile retain a more uniform temperature field. In the sectional center of the profiles made from the two different lubrications, extrusion with good lubrication results in greater grain/colony refinement due to greater effective strains, and a slightly greater dislocation density was found due to the uniform deformation. The tensile tests revealed that compared with poor lubrication, due to the improvement of Hall–Petch strengthening and dislocation strengthening in the cross-sectional center with good lubrication, the variation range of yield strength and tensile strength is reduced to 11 MPa and 7 MPa, respectively, and the variation range of microhardness is reduced to 44 HV and 32 HV, respectively. The improvement of lubrication not only helps to reduce forming defects but also can obtain uniform mechanical properties. [ABSTRACT FROM AUTHOR]

The spread of 3D printing in many different fields has become eminent. This paper aims to improve the mechanical properties of parts printed by fused deposition modeling technique. Acrylonitrile butadiene styrene (ABS) specimens are printed with custom printing parameters. These parameters give a tensile strength that is 86% of the injection- molded ABS strength, and give one of the best recorded results for 100% infill printed ABS tensile specimens. Furthermore, a post filling technique has been studied. Specimens are printed with inner voids and different densities using slicing software. Void shape is precisely selected to conform to the filling process. High-strength, low-cost thermoset resin is injected through specimens to fill those voids. A tensile test has been performed after the full curing of the resin. A morphology analysis is done. Using this technique strength to printed weight ratio is improved by 151% and the cost is reduced by 51%. [ABSTRACT FROM AUTHOR]

The impact of water-induced degradation on the mechanical properties of the chosen two PTFE-coated, glass threads woven fabrics is investigated in this paper. The paper begins with a survey of literature concerning the investigation and determination of coated woven fabric properties. The authors carried out the uniaxial tensile tests with an application of flat and curved grips to establish the proper values of the ultimate tensile strength and the longitudinal stiffness of groups of specimens treated with different moisture conditions. Despite the water resistance of the main materials used for fabrics manufacturing, the change of the mechanical properties caused by the influence of water immersion has been noticed. The reduction in the tensile strength resulting under waterlogged is observed in the range from 5% to 16% depending on the type of investigated coated woven fabric and direction of weft or warp. [ABSTRACT FROM AUTHOR]

The microstructural stability and property evolution of high-temperature titanium alloys under long-term high-temperature conditions has been a critical scientific issue in the field of advanced titanium alloys. In this work, we systematically investigated the precipitation behavior of silicides and ordered α2 phase, which are closely related to the microstructural stability of Ti65 high-temperature alloy, during thermal exposure at 650 °C for different periods of time. Furthermore, the effects of thermal exposure on mechanical properties were evaluated using room temperature and high temperature tensile tests, and subsequently, the correlation between the microstructural thermal stability and the mechanical characteristics was discussed. The results reveal that (Ti, Zr)6Si3 silicides initially precipitate within the residual β film and then start to precipitate in the α platelet. A large number of fine spherical α2 precipitates were formed inside the α platelet after a short thermal exposure. The number density of ordered α2 decreased significantly after 1000 h due to Ostwald ripening. The precipitation of silicides and ordered α2 phases during thermal exposure improves the tensile strength but deteriorates the ductility, and the room-temperature ductility is slightly restored due to α2 ripening after long-time thermal exposure. Ti65 high-temperature titanium alloy consistently maintains favorable room-temperature tensile properties throughout long-term thermal exposure. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has various independent parameters that affect the mechanical properties and quality of the produced parts that are not linearly the function of each other. Process parameters in metal AM are very hard to control, analyse and optimise because they affect each other even though they can be independently changed. Changing process parameters in a wide range is not possible due to the formation of problems such as cracks, balling, unmelted powders, porosity and distortion. In this paper, a numerical model to predict the value of tensile strength of selective laser melting (SLM) Ti-6Al-4V parts and analyse the effect of process parameters on the results has been proposed. Taguchi L25 Design of Experiment (DOE) across 125 samples to create a comprehensive and general overview of influential parameters on the build process was investigated. Specifically, parameters included laser power, scan speed, hatch spacing, laser pattern angle and heat treatment (HT). To evaluate and analyse the build process according to established statistical variances, a minimum of five samples based on ASTM standard (for tensile test) were prepared. Heat treatment was added to the DOE to analyse the combined process and post-process effects. Results were compared (cross-validated) against existing values found in the literature and were found to effectively predict and explain the behaviour of tensile strength when changing process parameters. [ABSTRACT FROM AUTHOR]

This paper deals with various selective laser melting (SLM) processing strategies for aluminum 2618 powder in order to get material densities and properties close to conventionally-produced, high-strength 2618 alloy. To evaluate the influence of laser scanning strategies on the resulting porosity and mechanical properties a row of experiments was done. Three types of samples were used: single-track welds, bulk samples and samples for tensile testing. Single-track welds were used to find the appropriate processing parameters for achieving continuous and well-shaped welds. The bulk samples were built with different scanning strategies with the aim of reaching a low relative porosity of the material. The combination of the chessboard strategy with a 2 x 2 mm field size fabricated with an out-in spiral order was found to eliminate a major lack of fusion defects. However, small cracks in the material structure were found over the complete range of tested parameters. The decisive criteria was the elimination of small cracks that drastically reduced mechanical properties. Reduction of the thermal gradient using support structures or fabrication under elevated temperatures shows a promising approach to eliminating the cracks. Mechanical properties of samples produced by SLM were compared with the properties of extruded material. The results showed that the SLM-processed 2618 alloy could only reach one half of the yield strength and tensile strength of extruded material. This is mainly due to the occurrence of small cracks in the structure of the built material. [ABSTRACT FROM AUTHOR]

The present study introduces a novel approach utilizing machine learning techniques to predict the crucial mechanical properties of engineered cementitious composites (ECCs), spanning from typical to exceptionally high strength levels. These properties, including compressive strength, flexural strength, tensile strength, and tensile strain capacity, can not only be predicted but also precisely estimated. The investigation encompassed a meticulous compilation and examination of 1532 datasets sourced from pertinent research. Four machine learning algorithms, linear regression (LR), K nearest neighbors (KNN), random forest (RF), and extreme gradient boosting (XGB), were used to establish the prediction model of ECC mechanical properties and determine the optimal model. The optimal model was utilized to employ SHapley Additive exPlanations (SHAP) for scrutinizing feature importance and conducting an in-depth parametric analysis. Subsequently, a comprehensive control strategy was devised for ECC mechanical properties. This strategy can provide actionable guidance for ECC design, equipping engineers and professionals in civil engineering and material science to make informed decisions throughout their design endeavors. The results show that the RF model demonstrated the highest prediction accuracy for compressive strength and flexural strength, with R2 values of 0.92 and 0.91 on the test set. The XGB model outperformed in predicting tensile strength and tensile strain capacity, with R2 values of 0.87 and 0.80 on the test set, respectively. The prediction of tensile strain capacity was the least accurate. Meanwhile, the MAE of the tensile strain capacity was a mere 0.84%, smaller than the variability (1.77%) of the test results in previous research. Compressive strength and tensile strength demonstrated high sensitivity to variations in both water-cement ratio (W) and water reducer (WR). In contrast, flexural strength exhibited high sensitivity solely to changes in W. Conversely, the sensitivity of tensile strain capacity to input features was moderate and consistent. The mechanical attributes of ECC emerged from the combined effects of multiple positive and negative features. Notably, WR exerted the most significant influence on compressive strength among all features, whereas polyethylene (PE) fiber emerged as the primary driver affecting flexural strength, tensile strength, and tensile strain capacity. [ABSTRACT FROM AUTHOR]

Bamboo is a typical natural fiber-reinforced composite with excellent mechanical properties, which are determined by its special micro-structure. As the reinforcing phase, the vascular bundles play a central role in the control of the mechanical properties of bamboo macro-structure. To find the exact gradient variation of the mechanical properties of these continuously distributed vascular bundles within the bamboo culm, 4-year-old Moso bamboo was chosen to investigate the variation of locate-distribution, cross-section area, and mechanical properties of single vascular bundles along the longitudinal and radial directions with respect to their location from the base, middle, and top sections of bamboo culm, respectively. It shows that the spatial distribution of vascular bundles along the column is distributed exponentially from the inside to the outside of the culm. The cross-section area of the vascular bundles decreased exponentially from the inside to the outside along the radial direction. All the vascular bundles were then carefully separated from bamboo strips and tested via the tensile tests. Test results show that the longitudinal tensile strengths of vascular bundles ranged from 180.44 to 774.10 MPa, and the longitudinal Young's modulus ranged from 9.00 to 44.76 GPa. The tensile strength of vascular bundles at the outer side was three times higher than that of the inner side, while Young's modulus at the outer side was three to four times higher than that of the inner side. For all three height positions, the strengths and Young's modulus of vascular bundles are all exponentially increased from the inner side to the outer side along the radial direction. This work will provide a basis for the highly processed product's application of bamboo resources and a reference for further study on the trans-scale analysis of the mechanical properties of bamboo. [ABSTRACT FROM AUTHOR]

This study explores the mechanical properties of Glass Fiber-Reinforced Polymer (GFRP), a high-performance composite material, focusing on how varying diameters affect its tensile strength, modulus, and elongation. Experimental data obtained from three sets of tensile tests on 10, 12, and 25 mm bars helped establish a stress–strain relationship for GFRP reinforcements, considering diameter changes, and a formula for calculating the ultimate tensile strength based on diameter. Utilizing the weakest chain theory and the Weibull distribution, the research found that GFRP's tensile strength diminished with increased diameter, while the elastic modulus behaves oppositely. The analysis, grounded in the weakest chain theory, identifies the specimen's effective volume as a critical factor in the size effect of GFRP bars. Moreover, the study proves a significant size effect on GFRP's tensile properties, validating the theory's application in predicting the strength of GFRP bars of varying sizes and recommending a specimen length range of 30–40 times its diameter for standardization purposes. [ABSTRACT FROM AUTHOR]

The investigation of strain-rate effects on the mechanical response and characteristics of thin free-standing films is crucial for the design and fabrication of more reliable MEMS devices. It is also of high interest from the scientific and materials engineering views. In this paper we present a novel apparatus and a procedure for tensile testing of thin free-standing films under a wide range of strain rates from quasistatic to high, almost comparable with those obtained in Hopkinson bar tests. To provide this capability, a unique displacement measurement method is applied and a micro device which meets several strict requirements is implemented. We describe recent results of quasistatic experiments performed on pure aluminum free-standing thin films. A high rate experiment which demonstrates the setup capabilities is also presented. The micro-device measured properties are compared with finite element analysis results. [ABSTRACT FROM AUTHOR]

In the paper, the structure and static and dynamic mechanical properties of ultrafine-grained A5083 alloy (Al-Mg-Mn) produced by high-pressure torsion (HPT) are reported. The static yield stress and tensile strength were determined in tensile tests at a strain rate of ~ 10−3 s−1, and the dynamic yield stress and spall strength were calculated from free-surface velocity histories obtained during shock-wave loading at a strain rate of 105 s−1. The HPT technique provides strong grain refinement. The average grain size of the alloy after HPT is 100-180 nm and depends on the accumulated true strain. HPT significantly improves the static strength properties of the alloy. The static yield stress is increased by 360-390% and the static ultimate tensile strength by 166-182%. It is shown that the dynamic yield stress improved by 168-181%, while the dynamic spall strength was not improved by HPT. Moreover, the nanostructured alloy with a grain size of ~ 100 nm demonstrates the lowest spall strength. [ABSTRACT FROM AUTHOR]

Solid-state additive friction stir deposition (AFSD) is a thermomechanical-based additive manufacturing technique. For this study, AFSD was utilized to produce aluminum alloy 6061 (AA6061) blocks with varying layer thicknesses (1 mm, 2 mm, and 3 mm). The mechanical properties were assessed through uniaxial tensile tests and Vickers microhardness measurement, and statistical analysis was employed to investigate differences among data groups. The results revealed that the deposition layer thickness influences tensile properties in the building (Z) direction, while the properties in the X and Y directions showed minor differences across the three AFSD blocks. Furthermore, variations in tensile properties were observed depending on the sample orientation in the AFSD blocks and its depth-wise position in the part in the building direction. The microhardness values decreased non-linearly along the building direction, spread across the width of the part's cross-section, and highlighted that the deposition layer thickness significantly affects this property. The 1 mm block exhibited lower average microhardness values than the 2 mm and 3 mm blocks. The temperature histories and dynamic heat treatment are influenced by the deposition layer thickness and depend on the location of the point being studied in the part, resulting in variations in the microstructure and mechanical properties along the building direction and across the part's width. [ABSTRACT FROM AUTHOR]

Bimetallic tubes are used when a component requires more than one performance requirement, for instance, strength/creep resistance and oxidation/corrosion resistance. Shear-assisted processing and extrusion (ShAPE) can be used to fabricate extrudates that are comparable or superior in performance relative to conventionally manufactured extrudates. For the first time, ShAPE has been successfully employed in producing bimetallic Al tubing consisting of 6061 and 7075 Al alloys. Both light and electron microscopy techniques were used to investigate the integrity of the tubes, especially the interface between the core and cladding of the bimetallic tubes. Void-free bimetallic tubes were produced using ShAPE. Quantification of tube integrity was carried out with tensile testing under as-extruded and post-aged conditions. All the bimetallic tubes in the as-extruded samples exhibited uniform elongation above 5% with good tensile strength. Key insights such as material flow during bimetallic tube extrusion were obtained from the characterization of remnant billet and simulation results from a smoothed particle hydrodynamics model. [ABSTRACT FROM AUTHOR]

In this study, titanium (Ti) and manganese (Mn) element powders in determined amounts (0.35–0.75 and 1.5 wt %) were added into the 316 L stainless steel matrix by means of powder metallurgy (PM) technology, either individually or in pairs, and the desired composition was obtained as a powder mixture. The powders used in the study were cold-pressed tensile sample molds prepared in ASTM E8M standards, unidirectionally cold-pressed under 750 MPa compression pressure and formed into blocks. After pressing, the raw strength samples were sintered in an atmosphere-controlled tube furnace at 1250 °C for two hours in an argon atmosphere. The microstructure and mechanical properties of the produced PM steels were characterized using an optical microscope, SEM, EDS, tensile test, and hardness test. The results showed that the stainless steel samples with 0.35 (Ti and Mn) added to 316 L stainless steel had the highest yield strength, tensile strengths, and hardness strengths. However, with the addition of 0.75–1.5 Ti, 0.75–1.5 Mn and 0.75–1.5 (Ti and Mn) to 316 L stainless steel, a decrease was observed in the mechanical properties. Moreover, the stainless steel sample with 0.35 (Ti and Mn) added to 316 L stainless steel is better than other samples in terms of surface quality. [ABSTRACT FROM AUTHOR]

In the present study, AA7075 and AA2024 aluminum alloys were reinforced with ZrC, and the particles of WC were joined using the friction stir welding (FSW) method. The microstructural and mechanical properties of the welds were investigated using SEM, EDS, and tensile tests. The FSW process resulted in high-quality welds with fine grain structure; the stirred zone has 666% smaller grain size than AA7075 and AA2024 aluminum alloys. The tensile test showed strong and ductile welds. The fracture test showed ductile and less brittle composite joints of AA2024 and AA7075 alloys reinforced with WC and ZrC. The processing parameters in the FSW process significantly affect tensile strength (UTS); therefore, the improvement of UTS with tool speed is much greater than with welding speed. Increasing the tool speed from 400 to 560 rpm increased UTS by 7.1%, and from 560 to 700 rpm by 5.4%. The tensile test results showed that the welds exhibited considerable strength and ductility. Fracture analysis showed that the composite joints made of different AA2024 and AA7075 alloys and reinforced with WC and ZrC were ductile and less brittle. This study showed that FSW can efficiently fuse different aluminum alloys reinforced with ceramic particles. [ABSTRACT FROM AUTHOR]

The reuse system proposed by the authors is an overall business system for realizing a cyclic reuse flow through the processes of design, fabrication, construction, maintenance, demolition and storage. The reuse system is one of the methods to reduce the environmental burden in the field of building steel structures. These buildings are assumed to be demolished within approximately 30 years or more for physical, architectural, economic and social reasons in Japan. In this paper, focusing on building steel structures used for plants, warehouses and offices without fire protection, the performance of steel structural members for reuse is evaluated by a non-destructive test. First, performance evaluation procedures for a non-destructive test, such as mechanical properties, chemical compositions, dimension and degradation, are shown. Tensile strengths are estimated using Vickers hardness measured by a portable ultrasonic hardness tester, and chemical compositions are measured by a portable optical emission spectrometer. The weldability of steel structural members is estimated by carbon equivalent and weld crack sensitivity composition using chemical compositions. Finally, the material grade of structural members of the building steel structure for reuse is estimated based on the proposed procedures. [ABSTRACT FROM AUTHOR]

In the present paper, the Mg-11Gd-2Y-1Zn alloys with different Al addition were fabricated by the gravity permanent mold method. The effect of Al content on microstructure evolution and mechanical properties of as-cast Mg-11Gd-2Y-1Zn alloy was studied by metallographic microscope, scanning electron microscope, XRD and tensile testing. The experimental results showed that the microstructure of as-cast Mg-11Gd-2Y-1Zn alloy consisted of α-Mg phase and island-shaped Mg3 (RE, Zn) phase. When Al element was added, Al2RE phase and lamellar Mg12REZn (LPSO) phase were formed in the Mg-11Gd-2Y-1Zn alloy. With increasing Al content, LPSO phase and Mg3 (RE, Zn) phase gradually decreased, while Al2RE phase gradually increased. There were only α-Mg and Al2RE phases in the Mg-11Gd-2Y-1Zn-5Al alloy. With the increase of Al content, the grain size decreased firstly and then increased. When the Al content was 1 wt.%, the grain size of the alloy was the minimum value (28.9 μm). The ultimate tensile strength and elongation increased firstly and then decreased with increasing Al addition. And the fracture mode changed from intergranular fracture to transgranular fracture with increasing addition. When Al addition was 1 wt.%, the maximum ultimate tensile strength reached 225.6 MPa, and the elongation was 7.8%. When the content of Al element was 3 wt.%, the maximum elongation reached 10.2% and the ultimate tensile strength was 207.7 MPa. [ABSTRACT FROM AUTHOR]

Unfolding the structure–property linkages between the mechanical performance and microstructural characteristics could be an attractive pathway to develop new single- and polycrystalline Al-based alloys to achieve ambitious high strength and fuel economy goals. A lot of polycrystalline as-cast Al-Cu-Mg-Ag alloy systems fabricated by conventional casting techniques have been reported to date. However, no one has reported a comparison of mechanical and microstructural properties that simultaneously incorporates the effects of both alloy chemistry and mechanical testing environments for the as-cast Al-Cu-Mg-Ag alloy systems. This preliminary prospective paper presents the examined experimental results of two alloys (denoted Alloy 1 and Alloy 2), with constant Cu content of ~3 wt.%, Cu/Mg ratios of 12.60 and 6.30, and a constant Ag of 0.65 wt.%, and correlates the synergistic comparison of mechanical properties at room and elevated temperatures. According to experimental results, the effect of the precipitation state and the mechanical properties showed strong dependence on the composition and testing environments for peak-aged, heat-treated specimens. In the room-temperature mechanical testing scenario, the higher Cu/Mg ratio alloy with Mg content of 0.23 wt.% (Alloy 1) possessed higher ultimate tensile strength when compared to the low Cu/Mg ratio with Mg content of 0.47 wt.% (Alloy 2). From phase constitution analysis, it is inferred that the increase in strength for Alloy 1 under room-temperature tensile testing is mainly ascribable to the small grain size and fine and uniform distribution of θ precipitates, which provided a barrier to slip by deaccelerating the dislocation movement in the room-temperature environment. Meanwhile, Alloy 2 showed significantly less degradation of mechanical strength under high-temperature tensile testing. Indeed, in most cases, low Cu/Mg ratios had a strong influence on the copious precipitation of thermally stable omega phase, which is known to be a major strengthening phase at elevated temperatures in the Al-Cu-Mg-Ag alloying system. Consequently, it is rationally suggested that in the high-temperature testing scenario, the improvement in mechanical and/or thermal stability in the case of the Alloy 2 specimen was mainly due to its compositional design. [ABSTRACT FROM AUTHOR]

The mechanical performance and structural evolution of a flexible laminated composite envelope material after 5 years of service were investigated by uniaxial tensile test and interfacial peeling test. Compared with a pristine material, the post-utilized envelope material degraded severely in the aspects of surface appearance, intrinsic structure, and tensile strength owing to the erosion caused by a harsh environment. To determine the structural aging and mechanical property deterioration mechanism, wide-angle X-ray diffraction and attenuated total reflection Fourier transform infrared were performed on specific structural components of the envelope material. The structural causes of mechanical property degradation of the post-utilized envelope material are discussed in this paper in consideration of the coupling effects of multiple environmental factors (environmental load and radiation). The Graphical Abstract manifests the research procedure in this study. Accordingly, four aspects of material performance were characterized, including surface morphology, uniaxial tensile property, interfacial peeling behavior and cross-sectional structure. The mutual impact of the four above-mentioned material characteristic was then discussed, eventually leading to a clarification of the correlation between mechanical degradation and structural failure of composite envelope material. [Display omitted] [ABSTRACT FROM AUTHOR]

Research on pre-deformation influences on material properties in multistep hot forming is of important scientific interest. In this paper, hot tensile tests at 850 °C and a strain rate of 0.001 s−1 were performed to study the microstructural evolution and mechanical properties of Ti-6Al-4V with pre-strains at 0.05, 0.1 and 0.15. The tensile test results showed that the specimen with 0.05 pre-strain exhibited higher flow stress and larger elongation. Additionally, increasing the pre-strain resulted in a decrease in ultimate tensile strength (UTS) and elongation (EL). The EBSD results showed that the main deformation mechanism of Ti-6Al-4V was high-angle grain boundary sliding. Pre-strain promoted dynamic recrystallization (DRX) by increasing the deformation substructure. The refinement of grains and the eradication of dislocations enhanced the deformability, resulting in an increase in flow stress. [ABSTRACT FROM AUTHOR]

The paper presents the results of mechanical tests of models manufactured with two 3D printing technologies, FDM and CFF. Both technologies use PLA or PA-based materials reinforced with carbon fibers. The work includes both uniaxial tensile tests of the tested materials and metrological measurements of surfaces produced with two 3D printing technologies. The test results showed a significant influence of the type of technology on the strength of the models built and on the quality of the technological surface layer. After the analysis of the parameters of the primary profile, roughness and waviness, it can be clearly stated that the quality of the technological surface layer is much better for the models made with the CFF technology compared to the FDM technology. Furthermore, the tensile strength of the models manufactured of carbon fiber-enriched material is much higher for samples made with CFF technology compared to FDM. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) is a kind of stable material with excellent mechanical properties. Meshes made of PP have lots of obvious advantages. In this paper, 5 PP hernia meshes with different warp-knitting structures which can be sorted into one light-weight hernia mesh, two standard-weight hernia meshes and two heavyweight hernia meshes were chosen to have a serious of mechanical test, including weight density, thickness, pore size, porosity, tensile strength, bursting strength, stitch tear strength, tear strength and bending rigidity. The respective relationship between mechanical performance and weight density were analyzed. The results revealed that heavy-weight hernia meshes had the biggest thickness (0. 834 mm) , the smallest pore size (462 μm) and the smallest porosity (58.40%). The mechanical performance demonstrated that the tensile strength increased more than 800 N, the stitch tear strength increased more than 40 N, the bursting strength increased more than 750 N and the tear strength increased more than 40 N by enlarging the weight density by 100 - 150 g/m2. However, heavy-weight hernia meshes had problems of high bending rigidity, unevenness and anisotropy. Standard-weight hernia meshes with 70 -140 g/m2 not only met the demand of the mechanical properties, but also had good flexibility and structure parameters, which could be considered as an ideal hernia mesh. [ABSTRACT FROM AUTHOR]

The high aesthetic demands of patients have increased their requests to align their teeth using clear aligners, including Invisalign. Patients also want to have their teeth whitened for the same purpose; the use of Invisalign as a bleaching tray at night has been reported in few studies. However, whether 10% carbamide peroxide affects the physical properties of Invisalign is unknown. Therefore, the objective of this study was to evaluate the effect of 10% carbamide peroxide on the physical properties of Invisalign when used as a bleaching tray at night. Twenty-two unused Invisalign aligners (Santa Clara, CA, USA) were used to prepare 144 specimens to test their tensile strength, hardness, surface roughness, and translucency. The specimens were divided into four groups: a testing group at baseline (TG1), a testing group after application of bleaching material at 37 °C for 2 weeks (TG2), a control group at baseline (CG1), and a control group after immersion in distilled water at 37 °C for 2 weeks (CG2). Statistical analysis was conducted using a paired t-test, Wilcoxon signed rank test, independent samples t-test, and Mann–Whitney test to compare samples in CG2 to CG1, TG2 to TG1, and TG2 to CG2. Statistical analysis showed no statistically significant difference between the groups for all physical properties, except for hardness (p-value < 0.001) and surface roughness (p-value = 0.007 and p-value < 0.001 for the internal and external surface roughness, respectively), which revealed a reduction in hardness values (from 4.43 ± 0.86 N/mm2 to 2.2 ± 0.29 N/mm2) and an increase in surface roughness (from 1.6 ± 0.32 Ra to 1.93 ± 0.28 Ra and from 0.58 ± 0.12 Ra to 0.68 ± 0.13 Ra for the internal and external surface roughness, respectively) after 2 weeks of dental bleaching. Results showed that Invisalign can be used for dental bleaching without excessive distortion or degradation of the aligner material. However, future clinical trials are required to further assess the feasibility of using Invisalign for dental bleaching. [ABSTRACT FROM AUTHOR]

The proper process of preparing an adhesive composition has a significant impact on the degree of dispersion of the composition ingredients in the matrix, as well as on the degree of aeration of the resulting composition, which in turn directly affects the strength and functional properties of the obtained adhesive compositions. The paper presents the results of tensile strength tests and SEM microphotographs of the adhesive composition of Epidian 57 epoxy resin with Z-1 curing agent, which was modified using three fillers NanoBent ZR2 montmorillonite, CaCO3 calcium carbonate and CWZ-22 active carbon. For comparison purposes, samples made of unmodified composition were also tested. The compositions were prepared with the use of six mixing methods, with variable parameters such as type of mixer arm, deaeration and epoxy resin temperature. Then, three mixing speeds were applied: 460, 1170 and 2500 rpm. The analyses of the obtained results showed that the most effective tensile results were obtained in the case of mixing with the use of a dispersing disc mixer with preliminary heating of the epoxy resin to 50 °C and deaeration of the composition during mixing. The highest tensile strength of adhesive compositions was obtained at the highest mixing speed; however, the best repeatability of the results was observed at 1170 rpm mixing speed. Based on a comparison test of average values, it was observed that, in case of modified compositions, the values of average tensile strength obtained at mixing speeds at 1170 and 2500 rpm do not differ significantly with the assumed level of significance α = 0.05. [ABSTRACT FROM AUTHOR]

High-strength aluminum alloy (mainly refers to the 7xxx series) is the optimum material for lightweight military equipment. However, this type of aluminum alloy is a wrought aluminum alloy. If it is directly formed by traditional casting methods, there will inevitably be problems such as coarseness, unevenness, looseness, and hot cracking in the structure, which will greatly affect the final performance of the part. Based on the internal cooling with annular electromagnetic stirring (IC-AEMS) method, a new technology of rheological die forging is developed in this paper, and the scale-reduced parts of a brake hub of Al-6.54Zn-2.40Cu-2.35Mg-0.10Zr aluminum alloy were prepared. The influence of IC-AEMS and the addition of rare element Sc on the structure and mechanical properties of the parts was studied. An optical microscope and scanning electron microscope (SEM) were used to observe the microstructure evolution, energy dispersive spectroscopy (EDS) was used to analyze the phase distribution and composition, and the mechanical properties of the parts were tested by uniaxial tensile tests. The results show that the addition of Sc element can effectively refine the grains and improve the strength and elongation of the material; the application of IC-AEMS improves the cooling rate of the melt, increases the effective nucleation rate, and the grains are further refined. Through process optimization, scale-reduced parts of a brake hub with good formability and mechanical properties can be obtained, the ultimate tensile strength is 597.2 ± 3.1 MPa, the yield strength is 517.8 ± 4.3 MPa, and the elongation is 13.7 ± 1.3%. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of thermal cycling on mechanical degradation of polymer matrix composites (PMCs). Un-notched and open-hole specimens are tested using developed thermal cycling apparatus and tensile test machine. In addition, the hole-size effect of open-hole tension glass/epoxy composite laminates is investigated. The tensile strength, mass loss and surface degradation of the specimens were obtained during 250 cycles. Experimental results showed that the holes diameter is the main parameter to control the thermal cycling effects on open hole structure. Also, it is found that laminates with smaller holes have higher tensile strength variation than those with larger holes. The results showed that increment of the hole diameter and number of cycles decreases the tensile strength. [ABSTRACT FROM AUTHOR]

Chitosan (CS) fibers have been applied in various fields due to their biocompatibility, biodegradability, and antibacterial properties. However, weak mechanical properties remain as obstacles to further applications. Silk nanofibrils (SNFs) extracted from natural silk fibroin fibers preserve outstanding mechanical properties at the nanoscale, which are expected to impact structural programming and mechanical reinforcement for CS fibers. In this study, wet‐spun CS/SNFs composite fibers were continuously collected from NaOH/ethanol coagulation. Scanning electron microscope (SEM) results showed that SNFs were uniformly distributed in the CS matrix, and obvious orientation was observed when the mass ratio of SNF/CS was 75/100. Tensile tests showed that the introduction of SNFs significantly enhanced the mechanical properties of CS fibers when the mass ratio of SNF/CS was more than 25/100. With the increasing of SNF content, the tensile strength gradually increased, and the tensile strength and modulus could be increased 2.9 times and 3.5 times, respectively, when 100% SNF was added. The improvement of mechanical properties was partially attributed to hydrogen bonding between SNF filaments and CS, which was confirmed by FTIR and XRD results. This study provides a facile and eco‐friendly method to spin CS fibers with enhanced mechanical properties and a hierarchical structure. [ABSTRACT FROM AUTHOR]

Two novel ignition-resistant magnesium alloys, Mg-2Gd-2Y-1Ca and Mg-2Nd-1Y-1Ca, were prepared in the ultrafine-grain condition by equal channel angular pressing (ECAP). In addition, four commercial alloys—AZ31, AX41, AE42 and WE43—were prepared similarly as a reference. The microstructure, mechanical properties and ignition temperature were thoroughly investigated. Both novel alloys exhibited a mean grain size of ~1 µm and dense distribution of small secondary phase particles. The mechanical strength measured by the tensile deformation test showed that the novel alloys are much stronger (~290 MPa) than all commercial alloys except WE43. However, Ca segregation into the grain boundaries caused a significant decrease in ductility (<6%). The ignition temperature of the novel alloys (~950 °C) was considerably improved by the presence of Gd/Nd, Y and Ca. This study showed that both novel alloys exhibit high strength and high ignition temperature in the ultrafine-grain condition. [ABSTRACT FROM AUTHOR]

In this paper, the microstructure and mechanical properties of two magnesium matrix composites—a hypoeutectic with 1.9 wt% Mg2Si phase and a hypereutectic with 19 wt% Mg2Si compound—were analyzed. The investigated materials were prepared using the gravity casting method. Microstructure analyses of the fabricated composites were carried out by XRD and light microscopy. The tensile and compression strength as well as yield strength of the composites were examined in both uniaxial tensile and compression tests. The microstructure of the hypoeutectic composite was in agreement with the phase diagram and composed of primary Mg dendrites and an Mg–Mg2Si eutectic mixture. For the hypereutectic composite, besides the primary Mg2Si phase and eutectic mixture, additional magnesium dendrites surrounding the Mg2Si compound were observed due to nonequilibrium solidification conditions. The composites exhibited a rise in the examined mechanical properties with an increase in the Mg2Si weight fraction and also a higher tensile and compression strength in comparison to the pure magnesium matrix (cast in the same conditions). Additionally, analyses of fracture surfaces of the composites carried out using scanning electron microscopy (SEM + EDX) are presented. [ABSTRACT FROM AUTHOR]

The superficial effect of hardening caused after vibration-assisted ball burnishing and its consequences in the tensile behavior of a carbon steel material are studied in this paper. As ball burnishing affects the material to hundredths of micrometers in depth through plastic deformation, the overall macro effect of this modification was studied. Different levels of preload and vibration amplitude were studied to address the described issue. The study was done in two phases. First of all, the depth to which ball burnishing affects the material was studied by performing Vickers indentation tests with different loads. It was proven that the effects of ball burnishing are best represented when a 0.05 kg load is used, as higher loads include more volume of core material in the measurement, hence hiding the effect of ball burnishing. In a second phase, the ball burnished specimens were subjected to tensile tests. It was proven that an increase of burnishing preload diminishes the ductile behavior of the material and increases its strength representative values, although the proportion of affected material in the cross-section of the specimen is reduced with regard to the whole surface. Additionally, as the preload increases, the effects of assistance through vibrations is reduced, and the effect of the static preload acquires more relevance in modifying the macroscopic mechanical properties of the steel alloy. Experiments using different amplitudes and new forces are encouraged to obtain more information about how the material can be modified optimally through vibration-assisted ball burnishing. [ABSTRACT FROM AUTHOR]

Wire Arc Additive Manufacturing (WAAM) is one of the most appropriate additive manufacturing techniques for producing large-scale metal components with a high deposition rate and low cost. Recently, the manufacture of nickel-based alloy (IN718) using WAAM technology has received increased attention due to its wide application in industry. However, insufficient information is available on the mechanical properties of WAAM IN718 alloy, for example in high-temperature testing. In this paper, the mechanical properties of IN718 specimens manufactured by the WAAM technique have been investigated by tensile tests and hardness measurements. The specific comparison is also made with the wrought IN718 alloy, while the microstructure was assessed by scanning electron microscopy and X-ray diffraction analysis. Fractographic studies were carried out on the specimens to understand the fracture behavior. It was shown that the yield strength and hardness of WAAM IN718 alloy is higher than that of the wrought alloy IN718, while the ultimate tensile strength of the WAAM alloys is difficult to assess at lower temperatures. The microstructure analysis shows the presence of precipitates (laves phase) in WAAM IN718 alloy. Finally, the effect of precipitation on the mechanical properties of the WAAM IN718 alloy was discussed in detail. [ABSTRACT FROM AUTHOR]

In this study, pure titanium equivalent to Grade 1 was subjected to tensile tests at strain rates ranging from 10−6 to 100 s−1 to investigate the relationship between its mechanical properties and its twinning and slip. Deformation properties and microstructures of samples having average grain sizes of 210 μm (Ti-210), 30 μm (Ti-30), and 5 μm (Ti-5) were evaluated. With increasing strain rates, the 0.2% proof stress and ultimate tensile strength increased for all samples; the fracture strain increased for Ti-210, decreased for Ti-5, and changed negligibly for Ti-30. Comparing high (100 s−1) and low (10−6 s−1) strain rates, twinning occurred more frequently in Ti-30 and Ti-210 at high strain rates, but the frequency did not change in Ti-5. The frequency of 1st order pyramidal slip tended to be higher in Ti-30 and Ti-5 at low strain rates. The higher ductility exhibited by Ti-210 at high strain rates was attributed to the high frequency of twinning. In contrast, the higher ductility of Ti-5 at low strain rates was attributed to the activity of the 1st order pyramidal slip. [ABSTRACT FROM AUTHOR]

It is important to have an understanding of the mechanical properties of crisp pears in order to assess their resistance to damage and investigate their compression patterns. Through tensile and compression tests, this study measured the elastic modulus, tensile strength, compressive strength and other parameters of Pucheng Crisp Pear, explored the effect of storage temperature on the mechanical properties of crisp pears, and developed a storage temperature-mechanical property prediction model. The results of the pear peel tensile test showed that both the tensile strength of the peel decreased with the increase of storage temperature, while the modulus of elasticity was decreased. There were no significant differences in the tensile strength and modulus of elasticity of the peel at the same storage temperature. The results of the flesh compression test also showed a decrease in compressive strength and modulus of elasticity with increasing storage temperature. Under the same storage condition, the compressive strength and modulus of elasticity of the pear flesh differed significantly in different directions. The correlation coefficients for tensile strength and modulus of elasticity in both the axial and radial directions for the peel and flesh of crisp pears were high, and provided accurate predictions for mechanical characteristics. These findings could be used to inform the development of mechanical equipment, post-harvest storage methods, and the reduction of mechanical damage in all working stages of crisp pears. [ABSTRACT FROM AUTHOR]

Štore Steel Ltd. is one of the biggest flat spring steel producers in Europe. The main motive for this study was to study the influences of non-metallic inclusions on mechanical properties obtained by tensile testing. From January 2016 to December 2021, all available tensile strength data (472 cases–472 test pieces) of 17 low alloy steel grades, which were ordered and used by the final user in rolled condition, were gathered. Based on the geometry of rolled bars, selected chemical composition, and average size of worst fields non-metallic inclusions (sulfur, silicate, aluminium and globular oxides), determined based on ASTM E45, several models for tensile strength, yield strength, percentage elongation, and percentage reduction area were obtained using linear regression and genetic programming. Based on modeling results in the period from January 2022 to April 2022, five successively cast batches of 30MnVS6 were produced with a statistically significant reduction of content of silicon (t-test, p < 0.05). The content of silicate type of inclusions, yield, and tensile strength also changed statistically significantly (t-test, p < 0.05). The average yield and tensile strength increased from 458.5 MPa to 525.4 MPa and from 672.7 MPa to 754.0 MPa, respectively. It is necessary to emphasize that there were no statistically significant changes in other monitored parameters. [ABSTRACT FROM AUTHOR]

This work presents the manufacture of polymer composites using 3D woven structures (orthogonal, angle interlock and warp interlock) with glass multifilament tows and epoxy as the resin. The mechanical properties were analyzed by varying the processing parameters, namely, add-on percentage, amount of hardener, curing time, curing temperature and molding pressure, at four different levels during the composite fabrication for three different 3D woven structures. The mechanical properties of composites are affected by resin infusion or resin impregnation. Resin infusion depends on many processing conditions (temperature, pressure, viscosity and molding time), the structure of the reinforcement and the compatibility of the resin with the reinforcement. The samples were tested for tensile strength, tensile modulus, impact resistance and flexural strength. Optimal process parameters were identified for different 3D-woven-structure-based composites for obtaining optimal results for tensile strength, tensile modulus, impact resistance and flexural strength. The tensile strength, elongation at break and tensile modulus were found to be at a maximum for the angle interlock structure among the various 3D woven composites. A composition of 55% matrix (including 12% of hardener added) and 45% fiber were found to be optimal for the tensile and impact performance of 3D woven glass–epoxy composites. A curing temperature of about 140 °C seemed to be optimal for glass–epoxy composites. Increasing the molding pressure up to 12 bar helped with better penetration of the resin, resulting in higher tensile strength, modulus and impact performance. The optimal conditions for the best flexural performance in 3D woven glass–epoxy composites were 12% hardener, 140 °C curing temperature, 900 s curing time and 12 bar molding pressure. [ABSTRACT FROM AUTHOR]

Cross wedge rolling (CWR) has unique advantages in the production of shaft preforms with refined grains and improved mechanical properties. Considering the sensitivity of Ti-6Al-4V(TC4) alloy to heat treatment temperature, the effect of different initial deformation temperatures (IDTs) on the forming quality, mechanical properties, and microstructure evolution of the TC4 alloy lower arm preforms in CWR forming was studied in this work. The flow stress curves of TC4 alloy in the two-phase region were obtained by isothermal compression experiments. The Arrhenius constitutive model was established and applied to DEFORM-3D finite element (FE) software to simulate the CWR forming process of TC4 alloy lower arm preforms. The forming quality of TC4 alloy parts was compared and analyzed by 3D FE simulation and experiment. And their mechanical properties at room temperature were tested by tensile test. The results showed that the rolled part has well forming quality (no steps and necking defects) and higher geometric dimension accuracy at the IDT 885°C. Moreover, with the increase of IDT, the radial force and torque in the rolling process decrease. In addition, there were no internal defects in the parts rolled by different IDTs, because the die gap reduces the number of alternating cycles of tensile-compressive stress in the rolled workpieces. Compared with the initial state, the microstructure was refined. When the IDT is 885 °C, the ultimate tensile strength (UTS), yield strength (YS), and elongation (EI) of the parts were 987 MPa, 924 MPa, and 16.8%, respectively, which was able to ensure the mechanical performance requirements of the lower arm preform. The results provide theoretical guidance for the actual production of lower arm preform by CWR. [ABSTRACT FROM AUTHOR]

The effect of process parameters and the orientation of the cladding layer on the mechanical properties of 316L stainless steel components manufactured by laser metal deposition (LMD) was investigated. High aspect-ratio walls were manufactured with layers of a 4.5 mm wide single-cladding track to study the microstructure and mechanical properties along the length and the height of the wall. Samples for the tensile test (according to ASTM E-8M-04) were machined from the wall along both the direction of the layers and the direction perpendicular to them. Cross-sections of the LMD samples were analyzed by optical and scanning electron microscopy (SEM). The orientation of the growing grain was observed. It was associated with the thermal gradient through the building part. A homogeneous microstructure between consecutive layers and some degree of microporosity was observed by SEM. Uniaxial tension tests were performed on samples extracted from the wall in perpendicular and parallel directions. Results for ultimate tensile strength were similar in both cases and with the wrought material. The σ0.2 were similar in both cases but slightly superior to the wrought material. [ABSTRACT FROM AUTHOR]

In this paper, nanostructured multilayer with overall composition of Cu 53 Ni 47 was fabricated by means of accumulative roll bonding (ARB) of pure Cu and Ni metal strips. In the first four ARB cycles, the thickness reduction of the Cu layer was slow and twin boundaries were formed. Necking and fracture of the harder Ni layer happened and the Ni island-like areas were therefore formed. After four ARB cycles, the thickness of both Cu and Ni single layers became homogeneous and finally the single layer thickness less than 100 nm was formed after seven ARB cycles, corresponding to an equivalent strain of 11.11. 3DAP element concentration analysis confirmed that Cu–Ni solid solution was formed due to the inter-diffusion of the constituent elements across the interface, which increased the bonding strength of the adjacent layers. Tensile tests revealed that the ultimate tensile strength of the multilayer was up to 950 MPa, which is approximately five times higher than that of the initial pure Cu metal. For all the tensile specimens with various ARB cycles, debonding of the layer interface formed during the last ARB cycle was observed. The plastic strain first increased to a maximum value of 9.1% after four ARB cycles due to the homogenization of deformation between Cu and Ni single layer. Then the plastic strain decreased to about 4.6% after seven ARB cycles due to the formation of nanoscale microstructure. • Nanoscale Cu/Ni multilayer was fabricated by ARB up to seven cycles. • Cu–Ni solid solute was formed along the interface by mechanical alloying. • The nanoscale Cu/Ni multilayer showed maximum tensile strength of 950 MPa. • Debonding of the last formed interface occurred during tensile tests. [ABSTRACT FROM AUTHOR]

This work aims to study the influence of protective coatings on the water absorption and mechanical properties of 3D printed poly-lactic acid (PLA) parts. The PLA parts were fabricated with different levels of the 3D printing process parameters, aiming to define samples with distinct strength and ductility/toughness characteristics. Water absorption tests following the standard ASTM D570-98 were performed on uncoated and coated PLA specimens. The effectiveness of two protective coatings based on acrylic and polyurethane varnish on reducing water absorption was evaluated. Both protective coatings have shown being effective on preventing water absorption by the PLA, with polyurethane presenting the best performance reducing water absorption by 38%. Tensile tests were carried out to determine the ultimate tensile strength, elastic modulus, yield tensile strength, fracture strain and toughness of specimens, before and after the application of protective coatings. The polyurethane protective coating also benefits the tensile properties of PLA parts, increasing the strength and ductility/toughness characteristics of specimens up to 24%. [ABSTRACT FROM AUTHOR]

In this work, the effects of reclaimed sand additions on the microstructure characteristics, mechanical properties and fracture behavior of furan no-bake resin sand have been investigated systematically within the temperature range from 25 to 600 °C. The addition of 20%-100% reclaimed sand showed dramatic strength deterioration effect at the same temperature, which is associated with the formation of bonding bridges. Both the ultimate tensile strength (UTS) and compressive strength (CS) of the moulding sand initially increase with the increase of temperature, and then sharply decrease with the further increase of temperature, which is attributed to the thermal decomposition of furan resin. The addition amount of reclaimed sand has a remarkable effect on the room temperature fracture mode, i.e., with the addition of 0-20% reclaimed sand, the fracture mode was mainly cohesive fracture; the fracture mode converts to be mixture fracture mode as the addition of reclaimed sand increases to 35%-70%; further increasing the addition to 100% results in the fracture mode of typical adhesive fracture. The fracture surface of the bonding bridge changes from a semblance of cotton or holes to smooth with the increase of test temperature. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the effect of keeping constant the tool rotational speed to the welding speed ratio (ν ratio) on the mechanical properties of the dissimilar friction stir welding of EN AW6082-T6 and EN AW5083-H111. Two different pins shaped as triangular and pentagonal were associated with the constant ν ratio. From the tensile test results, it was found that the ν ratio does not create an evident change in the weld joint strength. The small cavity- and tunnel-type defects were observed at the nugget zone and located on the advancing side of the pin. These defects caused a decrease in the strength and elongation of the weld joint. The most important inference obtained from the experimental results is that if the ν ratio is kept constant, the weld joint strength for each weld does not correspond to a constant value. [ABSTRACT FROM AUTHOR]

The wide use of natural fibers has a long-standing history in Africa. In northern Angola, three native fiber plant species, namely Urena lobata, Triumfetta cordifolia, and Dombeya burgessiae, were investigated with regard to their potential usage in modern applications, such as green composites. Bast fibers of the three species were analyzed morphologically, chemically, and mechanically to determine properties such as fiber density, cellulose content, Young's modulus, tensile strength, and breaking strain. In comparison to other natural fibers, all three species were characterized by high Young's moduli up to 60 GPa and tensile strengths up to 950 MPa, yet retting is crucial to unfold the maximum strength of the fibers. Extending the retting time revealed higher values but probably negatively influences economic efficiency. The results demonstrated that the analyzed plants deliver strong and resistant fibers; based on their biomechanical performance, they are alternatives to commercially used natural fibers, such as jute (Corchorus spp.). However, as with other natural fibers, there was high variation in the mechanical properties in the studied species. [ABSTRACT FROM AUTHOR]

In recent years, to reduce cars costs, research has been conducted on dual-phase steels with low manganese content (below 1.0%). This study investigated the influence of technological parameters of heat treatment (heating temperature and cooling medium) on such steels' structures and mechanical properties. The ferrite-martensitic structures, specific for dual-phase steels, were obtained by intercritical quenching: heating of samples (made of alloys with 0.511% Mn, respectively 0.529% Mn) to temperatures located between critical points Ac1 and Ac3, followed by cooling in water without mechanical agitation and in water activated with ultrasounds at the frequency of 59 kHz. Through metallographic analyses and tensile tests, it was possible to determine the volume fraction of martensite, the ferrite microhardness, the ultimate tensile strength, the total elongation, and with the obtained data, their variations with the heating temperature and the cooling medium were established. Raising the heating temperature (between 760 °C and 820 °C) and using ultrasounds at cooling increased the volume fraction of martensite and the ferrite microhardness. This fact has increased the mechanical strength and reduced the deformability of the studied dual-phase steels. Intercritical quenching in water activated with ultrasounds provided values of structural characteristics and mechanical properties very close to those obtained by quenching in water without mechanical agitation, but was accomplished using a higher-temperature heating. The results obtained were compared with those determined in previous research, performed on dual-phase steel with 1.90% Mn. [ABSTRACT FROM AUTHOR]

This study aims to explore the tensile and impact properties (tensile strength, modulus of elasticity, and impact strength) of polypropylene (PP)-based nanocomposites reinforced with graphene nanosheets, nanoclay, and basalt fibers. The response surface methodology (RSM) with Box–Behnken design (BBD) was adopted as the experimental design. An internal mixer was used to prepare compounds consisting of 0, 0.75 and 1.5 wt% graphene nanosheets, 0, 10 and 20 wt% basalt fibers, and 0, 3 and 6 wt% nanoclay. The samples were prepared by a hot press machine for mechanical testing. The tensile tests were run to determine the tensile strength, and modulus of elasticity, and the Charpy impact tests were performed to assess the impact strength. It was found that the addition of basalt increased the tensile strength, modulus of elasticity, and impact strength by 32%, 64% and 18%, respectively. Also, the incorporation of the low-weight graphene nanosheets increased the tensile and impact strength by 15% and 20%, respectively, Adding graphene nanosheets generally improved the modulus of elasticity by 66%. Similarly, the addition of nanoclay improved the tensile strength by 17% and increased the modulus of elasticity by 59%, but further addition of it decreased the impact strength by 19%. The values obtained by this experiment for the mechanical property were roughly close to the data yielded from desirability optimization. [ABSTRACT FROM AUTHOR]

In this study, we prepared zinc wires with a diameter of 250 µm by direct extrusion using an extrusion ratio of 576. We studied the influence of the extrusion temperature and microstructure of the initial Zn billets on the microstructural and mechanical characteristics of the extruded wires. The extrusion temperature played a significant role in the final grain size. The wires extruded at 300 °C possessed a coarse-grained microstructure and the shape of their tensile stress–strain curves suggested that twinning played an important role during their deformation. A significant influence of the initial grain size on the final microstructure was observed after the extrusion at 100 °C. The wires prepared from the billet with a very coarse-grained microstructure possessed a bimodal grain size. A significant coarsening of their microstructure was observed after the tensile test. The wires prepared from the medium-grained billets at 100 °C were relatively coarse-grained, but their grain size was stable during the straining, resulting in the highest ultimate tensile strength. This preliminary study shows that strong attention should be paid to the extrusion parameters and the microstructure of the initial billets, because they significantly influence the microstructure and mechanical behavior of the obtained wires. [ABSTRACT FROM AUTHOR]