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This study demonstrates the feasibility of using Irvingia gabonensis shell particulates (IGSp) as alternative reinforcing materials in the development of aluminium-based composites. In this experimental study, the microstructure, phase composition, and mechanical behaviour of Al-10Zn-1.63Si/xIGSp (wt%, x = 1, 3, 5 and 7) composites were investigated. The Al-10Zn-1.63Si based composites were fabricated using the stir-casting technique. Different weight percentages (1, 3, 5 and 7) of IGSp were added to the Al-10Zn-1.63Si matrix. The chemical constituents of the IGSp were determined using X-ray fluorescence (XRF). The grain characteristics and phase(s) compositions were determined using Scanning Electron Microscopy (SEM) and X-ray diffractometer (XRD). The ultimate tensile strength, hardness, and impact strength of the developed composites were also determined. The SEM and XRD results revealed the presence of different phases: aluminium phosphate (Al16P16O64), gahnite (ZnAl2O4), andalusite (Al2SiO5), Quartz (SiO2) and aluminium silicate (Al2O3.5.SiO2). Results show that addition of IGSp led to an increase in ultimate tensile strength, with the highest value (128 MPa) obtained at 3 wt% IGSp. The hardness of the composites increased with increasing concentrations of IGSp, reaching a maximum value of 285 HV after adding 7 wt% IGSp. The impact strength improved with the addition of IGSp, with the highest value (30 J) obtained at 1 wt% IGSp. The improvements in mechanical properties were attributed to the dispersion of three major phases: aluminium silicate (Al2O3.54.SiO2), Al16P16O64 and Al2O3.54.SiO2. These phases contributed to the enhanced strength and hardness of the composites. The study noted a sudden decrease in ultimate tensile strength with higher concentrations of IGSp due to the increase in the intensities of Al16P16O64 and precipitation of hard but brittle new phase; Al2Si60.6O126.33. The study concludes that IGSp has the potential to serve as an alternative reinforcing material for aluminium-based composites. [ABSTRACT FROM AUTHOR]

This study focuses on evaluating the fatigue life performance of 3D-printed polymer composites produced through the fused deposition modelling (FDM) technique. Fatigue life assessment is essential in designing components for industries like aerospace, medical, and automotive, as it provides an estimate of the component's safe service life during operation. While there is a lack of detailed research on the fatigue behaviour of 3D-printed polymer composites, this paper aims to fill that gap. Fatigue tests were conducted on the 3D-printed polymer composites under various loading conditions, and static (tensile) tests were performed to determine their ultimate tensile strength. The fatigue testing load ranged from 80% to 98% of the total static load. The results showed that the fatigue life of the pressed samples using a platen press was significantly better than that of the non-pressed samples. Samples subjected to fatigue testing at 80% of the ultimate tensile strength (UTS) did not experience failure even after 1 million cycles, while samples tested at 90% of UTS failed after 50,000 cycles, with the failure being characterized as splitting and clamp area failure. This study also included a lap shear analysis of the 3D-printed samples, comparing those that were bonded using a two-part Araldite glue to those that were fabricated as a single piece using the Markforged Mark Two 3D printer. In summary, this study sheds light on the fatigue life performance of 3D-printed polymer composites fabricated using the FDM technique. The results suggest that the use of post-printing platen press improved the fatigue life of 3D-printed samples, and that single printed samples have better strength of about 265 MPa than adhesively bonded samples in which the strength was 56 MPa. [ABSTRACT FROM AUTHOR]

Additive Manufacturing (AM) processes are known as revolutionary manufacturing processes that fabricate a part using a 3D model layer upon layer. These techniques gained more attention from various industries due to their advantages like low waste material. Also, these processes can produce any part with high degrees of complexity in a short period of time. The Fused Deposition Modeling (FDM) process is a material extrusion-based technique which works by extruding a fine molten polymeric filament through a heated nozzle on the heated platform named printer bed. In this method, some important manufacturing parameters play a crucial role in controlling the mechanical properties and quality of the final fabricated part. However, all printed specimens through the FDM process should be tested based on the standards under some critical circumstances. Thus, in the current research paper, five and three test speeds are considered in tensile and fracture testing procedures, respectively to evaluate how these speeds can affect the mechanical and mode I fracture properties. Also, as the FDM specimens present elastic–plastic behavior, the critical value of J-integral is assumed as a fracture assessment and calculated from the finite element analysis. Among the mechanical properties, ultimate tensile strength is affected significantly by the test speed. For instance, the ultimate tensile strength of FDM specimens is 39.02, 38.58, 42.33, 48.09, and 52.11 for test speeds of 2, 4, 6, 8, and 10 mm/min, respectively. But vice-versa results are detected for the mode I fracture behavior and corresponding values of J for the FDM-PLA specimens. Finally, experimental and numerical results together with comprehensive discussions about the considered speeds and obtained results are reported. [ABSTRACT FROM AUTHOR]

Mg alloys with excellent high-temperature mechanical properties are urgently desired to meet the design requirements of new-generation aircraft. Herein, novel cast Mg-10Gd-2Y-0.4Zn-0.2Ca-0.5Zr-xAg alloys were designed and prepared according to the advantages of multi-component alloying. The SEM and XRD results revealed that the as-cast microstructures contained α-Mg grains, β, and Zr-containing phase. As Ag rose from 0 wt.% to 2.0 wt.%, the grain size was refined from 40.7 μm to 33.5 μm, and the β phase significantly increased. The TEM observations revealed that the nano-scaled γ′ phase could be induced to precipitate in the α-Mg matrix by the addition of Ag. The stacking sequence of lamellar γ′ phases is ABCA. The multiple strengthening phases, including β phase, γ′ phases, and Zr-containing particles, were effectively tailored through alloying and synergistically enhanced the mechanical properties. The ultimate tensile strength increased from 154.0 ± 3.5 MPa to 231.0 ± 4.0 MPa at 548 K when Ag was added from 0 to 2.0 wt.%. Compared to the Ag-free alloy, the as-cast alloy containing 2.0 wt.% Ag exhibited a minor reduction in ultimate tensile strength (7.0 ± 4.0 MPa) from 498 K to 548 K. The excellent high-temperature performance of the newly developed Mg-RE-Ag alloy has great value in promoting the use of Mg alloys in aviation industries. [ABSTRACT FROM AUTHOR]

(TiH2 + ScH3)/Al-Mg composite powders with different Ti contents were produced by ball milling. These composite powders were fabricated to cube and cuboid shape samples via a laser powder bed fusion process with optimal processing parameters. The TiH2 and ScH3 particles underwent dehydrogenation during the laser powder bed fusion process, and these composite powders ultimately formed Al-Mg-Sc-Ti alloys. The relative density, printability, microstructure, hardness and tensile properties of these alloy samples were investigated. The results show that these Al-Mg-Sc-Ti alloys have lower hot-crack sensitivity, having fine equiaxed grains. An Al18Mg3(Ti,Sc)2 intermetallic phase and in situ L12-Al3(Sc,Ti) precipitations formed during the laser powder bed fusion process, which is beneficial for nucleation and dispersion strengthening. The ultimate tensile strength of the Al-Mg-0.7Sc-1.0Ti alloy was 313.6 MPa with an elongation of 6.6%. During the hot isostatic pressing treatment, most of the Mg element precipitated from the matrix and changed the Al3(Sc,Ti) into a Al18Mg3(Ti,Sc)2 precipitate completely. The Al-Mg-Sc-Ti alloys were nearly fully dense after the hot isostatic pressing treatment and exhibited better mechanical properties. The ultimate tensile strength of the Al-Mg-0.7Sc-1.0Ti was 475 MPa with an elongation of 8.5%. [ABSTRACT FROM AUTHOR]

This study presents the adoption of the grey relational analysis (GRA) method and an objective weighting criterion (CRITIC) to select the best printing parameters (laser power, scan speed, hatch distance, and layer thickness) for achieving the minimum surface roughness. At the same time, the material hardness, ultimate tensile strength, elongation at break, and relative density are maximized and followed by a complementary residual stress assessment of selected samples. A Box Behnken experimental design of 27 experiments with a factor variation at three levels was chosen to characterize the laser-based powder bed fusion process of 316L stainless steel. This study is guided by a multi-criteria decision-making (MCDM) approach to simultaneously consider all the factors that yield the most proper printing parameters. Due to the multi-directionality of the problem analysed, four additional MCDM methods are also employed to avoid any limitations in the solutions. The correlation between these techniques was evaluated through Spearman's coefficient. Additionally, the reliability of the optimal printing outcomes was experimentally confirmed, improving the final surface quality by 8.17%, the elongation and ultimate tensile strength by 4.62% and 4.35%, respectively. Moreover, the residual stresses obtained were all of compressive nature, and their magnitude is comparable with those already published works. [ABSTRACT FROM AUTHOR]

In this research, effective utilization of agro waste breadfruit seed husk ash particle (SHA) as reinforcement purpose in LM25 alloy matrix enhanced with the inclusions of 3, 6, and 9wt% of graphite (Gr) nanoparticle (50nm) via squeeze cast liquid processing executed with 200MPa applied compressive pressure. This developed cast examined LM25 alloy and its composites for density, percentage of porosity, microstructure, ultimate tensile strength, abrasion, and corrosion behaviour. From the experimental result, the LM25/10wt% SHA/9wt% Gr hybrid nanocomposite has low density (2.554g/cc), an excellent ultimate tensile strength of (181±1.8 MPa), superior abrasion resistance (0.332mg/m) under 40N load at 0.75m/sec, and good corrosion resistance (0.00382mm/year) compared to cast LM25 alloy. The inclusions of SHA and Gr proved their presence in LM25 alloy has good mechanical strength and maximum abrasion and corrosion resistance to overcome the drawbacks of conventional stir-casted LM25 alloy, which is poor wear resistance. [ABSTRACT FROM AUTHOR]

Purpose: In recent years, additive manufacturing (AM) has started to be used for manufacturing real functional parts and assemblies for critical applications in aerospace, automotive, and machinery industries. Most complex or assembled parts require internal features (IF) such as holes, channels, slots, or guides for locational and mating requirements. Therefore, it is critical to understand and compare the structural and mechanical properties of additively manufactured and conventionally machined IFs. Design/methodology/approach: In this study, mechanical and microstructural properties of Inconel 718 (Inc718) alloy internal features, manufactured either as-built with AM or machining of additively manufactured (AMed) part thereafter were investigated. Findings: The results showed that the average ultimate tensile strength (UTS) of additively manufactured center internal feature (AM-IF) is almost analogous to the machined internal feature (M-IF). However, the yield strength of M-IF is greater than that of AM-IF due the greater surface roughness of the internal feature in AM-IF, which is deemed to surpass the effect of microstructure on the mechanical performance. The results of digital image correlation (DIC) analysis suggest that AM-IF and M-IF conditions have similar strain values under the same stress levels but the specimens with as built IF have a more locally ductile region around their IF, which is confirmed by hardness test results. But this does not change global elongation behavior. The microstructural evolution starting from as-built (AB) and heat-treated (HT) samples to specimens with IF are examined. The microstructure of HT specimens has bimodal grain structure with d phase while the AB specimens display a very fine dendritic microstructure with the presence of carbides. Although they both have close values, machined specimens have a higher frequency of finer grains based on SEM images. Originality/value: It was shown that the concurrent creation of the IF during AM can provide a final part with a preserved ultimate tensile strength and elongation but a decreased yield strength. The variation in UTS of AM-IF increases due to the surface roughness near the internal feature as compared to smooth internal surfaces in M-IF. Hence, the outcomes of this study are believed to be valuable for the industry in terms of determining the appropriate production strategy of parts with IF using AM and postprocessing processes. [ABSTRACT FROM AUTHOR]

Left ventricle leads are designed for the purpose of long-term pacing in the left ventricle. This study investigated the leads that use polyurethane as an outer insulator and SI-polyimide as an inner insulator. Polyurethane is commonly used for the outer insulation of cardiac leads due to its flexibility and biocompatibility. SI-polyimide (SI-PI) is a high-performance material known for its electrical insulation properties and is used for the inner insulation to maintain the integrity of the electrical pathways within the lead. Ten leads were received from the Wright State University Anatomical Gift Program. The duration of in vivo implantation varied for each lead, from less than a month to 108 months, with an average in vivo duration of 41 ± 31 months. We used the Test Resources Q series system for conducting our tests, as well as samples prepared to ensure compliance with the ASTM Standard D 1708-02a and the ASTM Standard D 412-06a. During the test, the load was applied to the intact lead. Before conducting individual tests, each lead was carefully inspected for surface defects. After conducting the tests, the load to failure, percentage of elongation, percentage of elongation at 5 N, ultimate tensile strength, and modulus of elasticity were calculated. There was no significant difference in load to failure, the percentage of elongation to failure, ultimate tensile strength, and modulus of elasticity (p-value = 0.82, p-value = 0.62, p-value = 0.82, and p-value = 0.12), respectively, when compared to in vivo exposure time. On the other hand, the percentage of elongation at 5 N force showed a significant difference (p-value = 0.0066) after 60 months in an in vivo environment. As the duration of in vivo exposure increased, the load to failure, percentage of elongation, ultimate tensile strength, and modulus of elasticity decreased insignificantly. The residual properties of these left ventricle leads remained relatively stable after 108 months of in vivo exposure duration, with no statistically significant degradation or changes in performance. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to determine the optimum parametric settings for yielding superior mechanical properties, namely, ultimate tensile strength (UTS), yield strength (YS) and percentage elongation (EL) of AZ91D/AgNPs/TiO2 hybrid composite fabricated by friction stir processing. Design/methodology/approach: An empirical model has been developed to govern crucial influencing parameters, namely, rotation speed (RS), tool transverse speed (TS), number of passes (NPS) and reinforcement fraction (RF) or weight percentage. Box Behnken design (BBD) with four input parameters and three levels of each parameter was used to design the experimental work, and analysis of variance (ANOVA) was used to check the acceptability of the developed model. Desirability function analysis (DFA) for a multiresponse optimization approach is integrated with response surface methodology (RSM). The individual desirability index (IDI) was calculated for each response, and a composite desirability index (CDI) was obtained. The optimal parametric settings were determined based on maximum CDI values. A confirmation test is also performed to compare the actual and predicted values of responses. Findings: The relationship between input parameters and output responses (UTS, YS, and EL) was investigated using the Box-Behnken design (BBD). Silver nanoparticles (AgNPs) and nano-sized titanium dioxide (TiO2) enhanced the ultimate tensile strength and yield strength. It was observed that the inclusion of AgNPs led to an increase in ductility, while the increase in the weight fraction of TiO2 resulted in a decrease in ductility. Practical implications: AZ91D/AgNPs/TiO2 hybrid composite finds enormous applications in biomedical implants, aerospace, sports and aerospace industries, especially where lightweight materials with high strength are critical. Originality/value: In terms of optimum value through desirability, the experimental trials yield the following results: maximum value of UTS (318.369 MPa), maximum value of YS (200.120 MPa) and EL (7.610) at 1,021 rpm of RS, 70 mm/min of TS, 4 NPS and level 3 of RF. [ABSTRACT FROM AUTHOR]

3D‐printed continuous fiber composites offer high strength in desired directions, which has attracted researchers' attention. In general, thermoset composites provide better results than their thermoplastics counterparts due to their higher modulus, low viscosity resin, better fiber impregnation, and proper adhesion to the reinforcing fibers. This study, examined the fabrication of continuous fiber‐reinforced thermoset composites (CFTCs) using 3D printing technology. This investigation focused on the optimization of process parameters for UV‐curable composites. Using systematic experimentation, the proper nozzle diameter (2.0 mm), print thickness (0.6 mm), and print speed (200 mm/min) were determined, resulting in the attainment of optimal fiber weight ratio and impregnation. The optimized CFTC exhibited an exceptional ultimate tensile strength of 276.26 MPa, exceeding existing literature data on printed short fiber composites. Additionally, under flexural loading conditions, an ultimate strength of 76.7 MPa was observed, which is characterized by a more ductile failure than a brittle fracture mode. The results of this research demonstrate the significant potential of 3D‐printed CFTCs and establish a robust process window for achieving exceptional mechanical properties. These findings hold promise for a wide range of applications demanding high‐strength composite materials. Highlights: Continuous fiber reinforced thermoset composites successfully printed.Determination of a process window for printed CFTCs.The optimized CFTC exhibited a remarkable ultimate tensile strength of 276.26 MPa.Ultimate strength of 76.7 MPa was achieved under flexural loading. [ABSTRACT FROM AUTHOR]

The ultimate tensile strength (UTS) of gray cast iron (GCI) can be affected by numerous parameters due to its complex microstructures. To further understand the UTS of GCI, it is necessary to evaluate the impact of various parameters. Herein, a UTS prediction method based on microstructure features and machine learning (ML) algorithms is proposed. The six regression algorithms, namely, Bayesian Ridge, Linear Regression, Elastic Net Regression, Support Vector Regression, Gradient Boosting Regressor (GBR), and Random Forest Regressor are used to develop the prediction models. The predicted results show that the GBR has the best prediction performance for the predicted UTS and the error bands within 5%. The feature importance indicates that matrix hardness has the greatest effect on the UTS in the ML models. [ABSTRACT FROM AUTHOR]

The current study aims to assess the impact of rheocast's input variables (cooling slope techniques) on its mechanical properties. The rheocast experiment was carried out by varying the input variables of slope angle (30º, 45º, and 60º), slope length (400, 500, and 600 mm), and pouring temperature (580, 585, and 590 °C). The effect of input variables on responses (ultimate tensile strength and elongation) and the factor interaction graph of responses have been evaluated by analysis of variance (ANOVA) and response surface methodology. The experimental findings showed that optimum response values (ultimate tensile strength, 181 MPa; elongation, 6.19%) were obtained at the following series of input variables: 585 °C pouring temperature, 500 mm slope length, and 45º slope angles. Analysis of variance results infers that pouring temperature is the most significant input variable, which highly influences the response factors. A confirmation experiment was performed at a 95% confidence level to ensure that the obtained values of response factors fall within permissible limits. [ABSTRACT FROM AUTHOR]

The use of materials for computer-aided design/computer-aided manufacturing (CAD/CAM) has been rapidly increasing in daily practice. However, one of the main issues regarding modern CAD/CAM materials is their aging in the oral environment, which may lead to significant changes in their overall properties. The aim of this study was to compare the flexural strength, water sorption, cross-link density (softening ratio%), surface roughness, and SEM analysis of three modern CAD/CAM "multicolor" composites. Grandio (Grandio disc multicolor—VOCO GmbH, Cuxhaven, Germany), Shofu (Shofu Block HC—Shofu Inc., Kyoto, Japan), and Vita (Vita Enamic multiColor—Vita Zahnfabrik, Bad Sackingen, Germany) were tested in this study. They were prepared in stick-shaped specimens and submitted to different tests after several aging protocols, such as thermocycling and mechanical cycle loading challenge. Further disc-shaped specimens were also created and tested for water sorption, cross-link density, surface roughness, and SEM ultramorphology, before and after storage in an ethanol-based solution. For flexural strength and ultimate tensile strength, Grandio showed the greatest values both at baseline and after aging (p < 0.05). Grandio and Vita Enamic presented the highest modulus of elasticity and the lowest water sorption (p < 0.05). A significant reduction (p < 0.05) in microhardness after ethanol storage (softening ratio%) was observed especially in Shofu. Grandio had the lowest roughness parameters compared to the other tested CAD/CAM materials, while ethanol storage significantly increased the Ra and RSm values in Shofu (p < 0.05). Despite the comparable modulus of elasticity of Vita and Grandio, this latter showed greater flexural strength and ultimate tensile strength both at baseline and after aging. Hence, Grandio and Vita Enamic may be employed for the anterior teeth and for those restorations requiring load-bearing capacity. Conversely, aging seems to affect several properties of Shofu, so its use for permanent restorations should be well-pondered based on the clinical situation. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to accomplish friction stir welding (FSW) of Al–Li alloy AA8090 to determine optimal settings of the process parameters for higher tensile strength and higher micro-hardness (MH) to achieve the objective of adequate butt-joint strength. Design/methodology/approach: An empirical relation is implemented to govern the utmost influence parameters, i.e. tool rotation speed (TRS), tool transverse speed (TTS) and dwell time (DT). Taguchi grey relational analysis (GRA) was applied for multi-response optimization of response parameters. The grey relational grades (GRs) have been calculated for both the responses MH and ultimate tensile strength to get optimal parametric settings. The variance test has been performed to check the adequacy of the model. Findings: The Taguchi L9 orthogonal array design was used in establishing the relation between input parameter and output parameter (tensile and MH). TTS and DT have been predicted to be the two most important parameters that influence the extreme quality features of joints by using friction stir welding. Scanning electron microscopy fractography shows the ductile failure of the welded joints. Originality/value: The experimental trials provided the followings results, maximum ultimate tensile strength (UTS) of 219 MPa and MH 107.1 HV under 1,400 rpm of TRS, 40 mm/min of TTS and 8 s of DT founded the optimum value through GRA. [ABSTRACT FROM AUTHOR]

Experimental investigations have been carried out to study the effect of Pd on the structure and physical properties of binary Ag100 –xPdx (at x = 40, 50, 60 at %) alloys. X-ray diffraction (XRD) patterns showed that these alloys form a face-centered cubic structure of A1 type. No superlattice peaks were observed in the diffraction patterns. Differential scanning calorimetry experiments revealed no phase transition in a temperature range of 25–1100°C. Results show that the addition of Pd leads to an increase in the value of electrical resistivity, whereas Vickers hardness and ultimate tensile strength decrease by increasing the concentration of Pd in these alloys. The results have been discussed and compared with those given in literature. [ABSTRACT FROM AUTHOR]

Titanium matrix composites (TMCs) have garnered substantial attention from researchers owing to their outstanding properties. Nonetheless, the strength and ductility of TMCs hardly co-exist and often show a trade-off between each other. In this study, we employ an ultra-thin graphite powder sheet as the carbon source and employ Ti/C composites with varying carbon contents, prepared via a layer-stacked laminated sintering method, to ensure a comprehensive in-situ reaction and uniform reinforcement distribution. With increasing carbon content, noticeable alterations occur in the size, concentration, and morphology of the titanium carbide (TiC) particles. The increase of TiC particle content is found to boost the ultimate tensile strength of the composite. However, this improvement comes at the expense of reduced elongation. Notably, as the carbon content reaches 1.81 wt%, the yield strength and ultimate tensile strength of the composites soar to 354.4 MPa and 575.4 MPa, respectively. These values represent a remarkable increase of 75.4% and 65.0% compared to pure titanium, while maintaining an acceptable elongation of 6.45%. This study unveils a promising approach for significantly enhancing the mechanical properties of titanium alloys. [ABSTRACT FROM AUTHOR]

Material extrusion is a popular additive manufacturing technology due to its low cost, wide market availability, ability to construct complex parts, safety, and cleanliness. However, optimizing the process parameters to obtain the best possible mechanical properties has not been extensively studied. This paper aims to develop ensemble learning-based models to predict the ultimate tensile strength, Young's modulus, and the strain at break of PLA and PLA-CF 3D-printed parts, using printing temperature, printing speed, and layer thickness as process parameters. Additionally, the study investigates the impact of process parameters and material selection on the mechanical properties of the printed parts and uses genetic algorithms for multi-objective optimization according to user specifications. The results indicate that process parameters and material selection significantly influence the mechanical properties of the printed parts. The ensemble learning predictive models yielded an R2 value of 91.75% for ultimate tensile strength, 94.08% for Young's modulus, and 88.54% for strain at break. The genetic algorithm successfully identified optimal parameter values for the desired mechanical properties. For optimal ultimate tensile strength, PLA-CF was used at 222.28 °C, 0.261 mm layer, 40.30 mm/s speed, yielding 41.129 MPa. For Young's modulus: 4423.63 MPa, PLA-CF, 200.01 °C, 0.388 mm layer, 40.38 mm/s. For strain at break: 2.249%, PLA, 200.34 °C, 0.390 mm layer, 45.30 mm/s. Moreover, this work is the first to model the process–structure property relationships for an additive manufacturing process and to use a multi-objective optimization approach for multiple mechanical properties, utilizing ensemble learning-based algorithms and genetic algorithms. [ABSTRACT FROM AUTHOR]

This study presents an experimental investigation on the structural effects of an ignited fire occurring in a steel warehouse building with storage racks located at a part of an industrial plant. In order to judge whether the structure needs to be dismantled, repaired, or reused after the fire, an on-site postfire damage reconnaissance study was conducted, and postfire mechanical properties, such as tensile tests and Charpy V-notch impact tests, and chemical analysis of the structural steels used for the building, were determined depending on specimens removed from the fire-damaged structural steel members. The bearing system of the one story industrial steel building having a span of 25 m consisted of 12 fixed supported rigid gabled moment frames with rafters and 12 m high columns of H Section (HEA) 360. At the roof, the bracings of circular hollow section (CHS) 114.3×3.0 and the purlins of C180 were used, while at the level of 8.9 m, crane beams were designed as HEA 600. From the tensile and impact tests, stress-strain curves, yield strength, ultimate tensile strength, elongation at fracture, and impact energy of the steel specimens were achieved. After all the results obtained from the tests performed at room temperature were evaluated, it was concluded that the structural steel elements affected but showing no distortions after the fire could be reused conveniently. In addition, the proposed approach to estimate the temperature exposed by the structural steels during the fire could have the potential to contribute to the existing relevant literature. In this study, it is experimentally explained what can be done about whether a steel structure needs to be dismantled, repaired, or reused after a fire event. First performing on-site damage detection and then taking samples from the structural load bearing system members' chemical and mechanical tests should be carried out. Depending on the site investigation, it can be easily considered that the heavily deformed structural steel members become unusable and need to be renewed. From the tensile and impact tests of the structural steel elements affected but showing no distortions after the fire, their postfire mechanical properties are vital and should be ascertained. After all the test results were obtained, it can be concluded whether the structural steel members affected by fire can be reused, or need to be repaired or removed. In terms of ductility and elastic-perfectly plastic properties, it has been observed that after the fire the steel structural members showing no or even slight distortions can be reused conveniently. Thus, due to high cost of reconstruction of a steel building, a meaningful economy as well as acquisition in time can be achieved with this approach. [ABSTRACT FROM AUTHOR]

Selective laser melting is an additive manufacturing technology whereby parts are built through selective melt of a powder bed by a laser beam. This technology is used to produce net shape parts in 3D printers. In this study, the effect of selective laser melting parameters on the mechanical properties (ultimate tensile strength and hardness) of iron has been experimentally extracted, and the optimum levels of the parameters have been determined for optimum mechanical properties using signal‐to‐noise analysis. The selected parameters include the laser power, the laser scanning speed, and the laser hatch distance, and the design of experiments was done by the Taguchi method. The main effects of factors and interactions were considered in this paper. The results show that the optimum parameter levels for the ultimate tensile strength include the laser power of 200 W, the laser scanning speed of 600 mm/s, and the hatch distance of 70 μm. The optimal parameters for hardness are similar to the maximum tensile strength, except that the optimum hatch distance is 60 μm. [ABSTRACT FROM AUTHOR]

Selective laser sintering (SLS) is one of the additive manufacturing technologies dedicated to the production of high-quality parts with complex geometries. Here, polyamide 12 (PA12) is a commonly used material, for manufacturing parts with sufficient mechanical and thermal properties. In SLS, many manufacturing parameters have an effect on the mechanical properties of final parts. Even the decision regarding the orientation of a part in a powder bed may have a significant effect on the mechanical properties. In this research, the influence of horizontal (H) and vertical (V) printing orientations on the ultimate tensile strength (UTS) of fabricated PA12 specimens are examined. Our research findings show that H specimens exhibit larger deformations and smaller UTS value scatter in comparison with V specimens. Also, worth pointing out is the fact that V-oriented specimens have a higher elastic modulus. One can assume that the sintering process is more effective in V specimens, due to a more uniform laser beam trajectory than in the H specimens' case. [ABSTRACT FROM AUTHOR]

The present study aims to investigate the effect of the mechanical and metallurgical joint strength behavior of Cr-Ni-Mo steel (AISI 316) using direct drive friction welding. Experimental procedures in the study included macrostructure, microhardness, tensile test specimens with effective diameters of 4 mm, 6 mm, and 8 mm, microstructure of the fracture position, and tensile fracture morphology. The results concluded that the average microhardness values for 4 mm, 6 mm, and 8 mm diameter around the weld interface center are 298 Hv0.1, 300 Hv0.1, and 295 Hv0.1, respectively. The ultimate tensile strength ratios were of 95%, 98%, and 97% for 4 mm, 6 mm, and 8 mm, respectively, while, the ductility increased with the diameters of 41%, 50%, and 57% for 4 mm, 6 mm, and 8 mm, respectively, compared to AISI 316. The fracture position for all welded joints was in the adjacent region to the interface. The fracture surfaces had a fingerprint form and ductile mode at cleavage features. The center of the fracture revealed different forms of dimples and microcavities collected at that center. [ABSTRACT FROM AUTHOR]

The mechanical properties, including tensile and impact properties at different testing temperatures of alumina‐forming austenitic steels (25 % nickel, 20 % chromium) with different aluminum contents (0, 2.5 %, 5 % and 8 %) were investigated. Scanning and transmission electron microscopy together with tensile and impact properties tests were conducted. The results showed that the tensile strength of steels at 298 K increased obviously along with aluminum contents increasing, while plasticity decreased at the same, which attributed to the higher volume fraction and number density of spherical NiAl precipitation together with main ferrite in matrix. In addition, spherical NiAl particles dispersed easily in ferrite. In particular, the ultimate tensile strength of the sample with 8 % aluminum could reach 1398 MPa, with the elongation of 14 % at 298 K. However, NiAl precipitations would lose strengthening effects at high temperatures, but the plasticity could be improved. In addition, the sample with 5 % aluminum showed better comprehensive properties by comparison to other samples, and the ultimate tensile strength was 1018 MPa and 491 MPa at 298 K and 973 K with the elongation of 26 % and 43 %, respectively, enabling it to be promising material for industrial application in advanced nuclear systems. [ABSTRACT FROM AUTHOR]

The hypoeutectic aluminum alloy AlSi5Cu2Mg is used for the production of high-strength cylinder head castings. The alloy is unique for its specific low permitted Ti content (0.03 wt% max), which makes it impossible to refine the grain structure of this alloy using standard Al–Ti–B grain refiners. The specific chemical composition is specified by the supplier company. The aim of this paper is to find a suitable alloying element that would improve the selected properties (e.g., mechanical, and physical properties) that are crucial for cylinder head castings. The research focuses on the investigation of the effect of different Zr addition (0.05; 0.10; 0.15 and 0.20 wt% Zr in the form of AlZr20 master alloy) on the properties of AlSi5Cu2Mg in the as-cast state and after heat treatment T7. The obtained results showed that ultimate tensile strength, yield strength, hardness, and physical properties of as-cast samples do not change significantly with increasing Zr content. The experimental alloys showed a more significant increase in ultimate tensile strength, yield strength, hardness, and thermal conductivity after heat treatment T7. Zirconium-rich intermetallic phases were observed in the shape of separate thick needles or as a cluster of two crossed thinner needles. [ABSTRACT FROM AUTHOR]

This study investigates the relationship between four welding input parameters (voltage, current, heat input, and welding speed) and the ultimate tensile strength (UTS) and yield strength (YS) of a welded joint. The work joined two super-duplex stainless-steel pipes of outside diameter 0.630 inches (16.002 mm) and a thickness of 0.065 (1.651 mm), using Gas Tungsten Arc Welding. Factorial design was used to ascertain the main and interaction effects of the welding input parameters on the UTS and YS of the welded joint. Results revealed a significant interaction between voltage, current, welding speed and heat input for UTS, and a significant interaction between the welding speed and heat input for YS. Results further revealed that as voltage increases from 9.3 V to 11.6 V, the UTS decreases by 2.69 MPa, while YS increases significantly by 24.25 MPa. When the current increases from 30 A to 38 A, the UTS increases by 10.81 MPa, while the YS increases by 4.25 MPa. In the case of the welding speed, an increase from 0.46 to 0.71 mm/s results in a decrease of the UTS by 7.94 MPa and a significant increase of the YS by 33.25 MPa. When the heat input increases from 0.54 to 0.70 kJ/mm, the UTS decreases by 15.06 MPa, whereas the YS decreases significantly by 35.25 MPa. Also, the optimum voltage, current, welding speed and heat input for UTS are 11.60 V, 30.0 A, 0.71 mm/s, and 0.70 kJ/mm, respectively, and those of YS are 9.30 V, 30.0 A, 0.46 mm/s, and 0.70 kJ/mm, respectively. [ABSTRACT FROM AUTHOR]

Abstract In this study, a criterion for optimizing the fatigue strength of metallic materials is proposed, and verified by many experimental results. The strategy for optimizing the fatigue strength is to continuously increase the ultimate tensile strength (UTS) under the condition of keeping certain work-hardening abilities. It is found that the relationship between the true UTS and true uniform elongation can be described by two straight lines, and the optimal fatigue strength can be obtained at the point where the two straight lines intersect with each other. This study has great guiding significance for economizing time and money to optimize the fatigue strength of metallic materials. [ABSTRACT FROM AUTHOR]

The concepts and inspiration of biological evolution in nature are used to create new and effective competing tactics in the burgeoning field of bio-inspired computing optimization algorithms. In the present work, nine specimens of similar alloys i.e., AA6262 were Friction Stir Welded. Tool Rotational Speed (RPM), Traverse Speed (mm/min), and Plunge Depth (mm) were the input parameters while the Ultimate Tensile Strength (MPa) was an output parameter. The main objective of the work is to obtain the maximum optimized Ultimate Tensile Strength (MPa) by using Bio-Inspired Artificial Intelligence Algorithms i.e., Differential Evolution and Max Lipschitz optimization (Max LIPO) Algorithm. The results showed that the Differential Evolution algorithm resulted in a slightly higher value of the Ultimate Tensile Strength of 184.87 MPa in comparison to the Max LIPO algorithm which resulted in the Ultimate Tensile Strength value of 183.94 MPa. [ABSTRACT FROM AUTHOR]

Metals often lose their ductility at cryogenic temperatures owing to the decreased mobility of dislocations. TRansformation-induced plasticity (TRIP), a toughening mechanism at room temperature, can increase damage susceptibility at low temperatures, as the resultant martensite phases can become more brittle than the parent phases. Herein, we develop a high-entropy alloy (HEA) with an improved low-temperature impact-damage tolerance through a sequential plasticity mechanism. We design a trip-assisted dual-phase HEA (TADP HEA) and investigate the effects of Al addition on its mechanical properties upon deformation at different temperatures, depending on stacking fault energy (SFE). Our analysis shows that a senary (Cr20Mn6Fe34Co34Ni6)98Al2 HEA exhibits superior mechanical properties, including a 641 MPa yield strength (σy), 964 MPa ultimate tensile strength (σUTS), and 40% uniform elongation (ɛUTS) at ambient temperature (25 °C), and a 1 GPa σy, 1.5 GPa σUTS, and 36% ɛUTS at −100 °C. Notably, despite the presence of hexagonal-close packed martensite, the HEA exhibits a higher Charpy impact energy (406 J) than Cantor HEA (344 J) at −100 °C. We attribute this improvement to the sequential deformation mechanism of mechanical twinning and martensitic transformation in the HEA at −100 °C, which results in sustainable steady strain-hardening during deformation. We suggest that optimizing the sequential deformation mechanism by manipulating SFE in multi-component alloys can be an effective route for improving the damage tolerance of metals at cryogenic temperatures. [ABSTRACT FROM AUTHOR]

Lattice distortion is considered to be one of the four core effects in a multicomponent high-entropy alloy. However, their effect is least understood from experiment and theoretical standpoints. The present investigation revealed a unique way to understand this effect by combining experiments with density functional theory (DFT) calculations. A small amount of Al and Si were carefully added to the whole-solute matrix of Cantor alloys. The different-sized atomic species introduces a huge lattice distortion in the matrix, leading to a simultaneous improvement in yield strength (YS), ultimate tensile strength (UTS), and percent elongation. An extensive DFT simulation indicates that a lattice distortion is prominent in an Al-containing alloy, whereas Si does not induce a lattice distortion. However, Si leads to severe interlayer lattice distortion, caused by the displacement of Si, during twinning. This leads to the improvement of YS, UTS, and ductility. Lattice distortion and its variants play significant effects on the mechanical properties of high-entropy alloys (HEAs) in terms of local lattice distortion, providing an uneven energy landscape for the movement of line defects or interlayer distortion. The inherent nature of local lattice distortion in HEAs leads to the wavy or tortuous dislocation, unlike a straight dislocation in conventional alloys. The movement of the wavy type of dislocation through a distorted or defective lattice requires large stress, resulting in a pronounced effect on solid solution strengthening. This local lattice distortion also dictates the degree of the interlayer distance distortion in the vicinity of atoms, leading to an increase or decrease in stable stacking fault energy that decides the deformation mode via slip or twinning. [ABSTRACT FROM AUTHOR]

Currently, in pipe welding, it is nearly difficult for a human welder to weld the whole circumference of a pipe in a single uninterrupted pass using MIG welding causing inconsistencies in weld quality around the welded pipe. The aim of this study was to develop an automated orbital pipe MIG welding system and to optimize welding parameters for enhancing ultimate tensile strength and Rockwell hardness of mild steel 1020 grade pipe. Three levels of variation were applied to the four input parameters that were chosen. Nine experiments were carried out using orthogonal array of L9. In this experimental investigation, the highest ultimate tensile strength (UTS) of 411.2 MPa and Rockwell hardness (RH) of 95 HRB were achieved at 110 A of current, 24 V of voltage, welding gun travel speed of 30 cm/min, and 3 mm of arc length. For modeling the orbital pipe MIG welding process experimental input parameters and response results, a hybrid artificial neural network and genetic algorithm (ANN-GA) model was constructed. This model was used to forecast and optimize UTS and RH, as well as the process factors that go with it. The results indicated that the ANN-GA model could predict the output responses with a mean square error of 5.06e-05. During optimization, a 4–9-2 network trained with neural network of back propagation by Bayesian regularization approach was determined to have the greatest prediction capability, with maximum UTS and RH of 417.857 MPa and 96.5364 HRB, respectively. From the confirmation tests, the average results of 412.7 MPa of UTS and 95 HRB of HR were obtained. The percentage of errors between the ANN-GA predicted optimal responses' results and the confirmatory experimental results were found 1.23% and 1.59% for UTS and RH, respectively. [ABSTRACT FROM AUTHOR]

In this study, the friction stir extrusion process as a new method was used to produce AA 1050 aluminum composite wires reinforced with silicon carbide (SiC) powder. The effect of process parameters on temperature (T), porosity (P) and ultimate tensile strength (UTS) was evaluated using the response surface method based on the Box-Behnken design. The input parameters included rotational speed (RS), extrusion force (EF) and reinforcement weight percentage (RF). Moreover, the microstructural evaluation of composite samples was conducted using optical microscope and scanning electron microscope. Finally, analysis of variance and regression analysis were used to obtain an appropriate model and confirm the accuracy of the results. The results showed that the temperature was increased by increasing the rotational speed to 1000 r/min and decreasing the extrusion force to 5.5 kN. Moreover, the lowest porosity value (averaged = 0.5%), and the highest tensile strength value (averaged = 153 MPa) were obtained at RS = 750 r/min, EF = 10.5 kN and RF = 3%. This can be attributed to the uniform distribution of reinforcing particles and strong interfacial bonding between SiC particles and the aluminum matrix. Also, the most effective parameter in the process was rotational speed which exhibited the greatest influence on P (53%) and UTS (41%) of composite samples. However, reinforcement weight percentage had the least effect on P (14%) and UTS (28%). [ABSTRACT FROM AUTHOR]

The energy efficiency of high-temperature batch aggregates largely depends on the modes of their heating and cooling. The modes of heating and cooling of aggregates in which thermal stress does not exceed the critical values of the ultimate strength of the refractories make it possible to increase their service life. The increase in the service life of refractories will lead to a reduction in the number of lining repairs and a decrease in the specific consumption of refractory materials per ton of technological product. Shorter warm-up and cool-down times result in lower energy consumption. Reducing the time for variable modes for casting ladles increases their turnover (the number of melt discharges into the ladle per day). Increasing ladle turnover not only reduces the number of ladles but also improves the economic performance of the enterprise. The ultimate strength of the refractory material significantly affects the rate of temperature change during heating and cooling of the refractory masonry. The purpose of this research is to study the dependence of the ultimate compression and tensile strengths of chamotte materials of the ShKU brand on temperature. The determination of the compression and tensile strengths was carried out on new samples of refractory materials as well as on samples of refractories that were in operation until the intermediate repair. To determine the ultimate compression strength of chamotte refractories, the standard technique for axial compression of the test specimen until its destruction was used. To determine the ultimate tensile strength, a three-point bending test was used with additional control of the surface temperature of the test sample during the test. The ultimate compression strength of chamotte refractories of the ShKU-32 brand increased for the new refractories by a maximum of 44%. For refractories that were in operation until the intermediate repair, the ultimate compression strength increased by a maximum of 56%. The value of the ultimate tensile strength at elevated temperatures turned out to be higher than the value at a temperature of 20 °C. For new refractories, the maximum ultimate tensile strength is 25% higher than the ultimate tensile strength under normal conditions. For refractories that were in operation until the intermediate repair, the maximum ultimate tensile strength increased by 24%. The obtained results can be used to increase the rate of heating or cooling of linings. [ABSTRACT FROM AUTHOR]

This study investigates the effect of extrusion speed during friction stir back extrusion on the microstructure, mechanical characteristics, and in vitro corrosion behavior of AZ91-3 vol % bioactive glass composite wire. To that end, the bioactive glass powder was inserted into the AZ91 matrix by drilling holes in the cross-section of the AZ91 rod. The results show that the extrusion speed strongly influenced the material's flow in the extruded wire's cross-section. By adding the bioactive glass powder to the processed wire, the ultimate tensile strength and corrosion resistance increased 5 and 23% compared to the additive-free wire. By decreasing the extrusion speed to 20 mm/min, the higher amount of discontinuous β -Mg 17 Al 12 phase and α + β eutectic formed in the grain boundaries. By applying the friction stir back extrusion process on the AZ91 rod a random crystallographic texture formed in the extruded wires. In the composite samples extruded at a rotational speed of 1200 rpm, a traverse speed of 20 mm/min, a gradient distribution, and improvement of mechanical properties (ultimate tensile strength of 332.95 MPa, yield strength of 268.33 MPa, and elongation of 9.89%) and corrosion rate (1.879 mm/year) at simulated body fluid were achieved. [ABSTRACT FROM AUTHOR]

The present work aims to develop nickel-based superalloys by studying the impact of their alloying elements in providing the desired physical and mechanical characteristics. At present, materials are being developed using experiment-driven trial and improvement. The long time duration in their development rules out the planning of new materials and thus leading engineers to select the commercially available materials with a compromise towards the properties. The computationally developed materials have the potential to meet the needs of the materials engineers, and now the materials are being brought into the centre of the planning method. The selection of suitable elemental composition seems to be a multi-criterion decision-making problem with conflicting and diverse objectives as different elements execute different properties at varied conditions. Nickel is an adaptable element that can alloy with most metals. The present study deals with the procedure that can be applied to identify suitable elemental composition for a Ni based super alloy, allowing them to adjust for required properties in order to enhance its use in a particular application. The methodology deals with the selection of 'n' number of alternatives to give desired properties and applying multi-criteria decision-making algorithms to rank and select one among the alternatives developed. The Spearman rank correlation coefficient in the range of 0.74-1.00 shown a strong correlation between the methods adopted. From the analysis Cr (wt. 12%), Co (wt. 16.5%), Mo (wt. 2.5%), W (wt. 1.5%), Nb (wt. 1.5%), Al (wt. 2%), Ti (wt. 3%), Fe (wt. 1.5%), C (wt. 0.2%), and B (wt.0.03%) can be developed to get an yield strength of 504.94 MPa, Ultimate tensile strength of 678.62 MPa, % elongation 18.53 and Creep resistance at 1000 hours work life of 263 MPa to get better ductile properties. Also Cr (wt. 18%), Co (wt. 17%), Mo (wt. 4%), W (wt. 2%), Al (wt. 2%), Ti (wt. 1.5%), Fe (wt. 2%), C (wt. 0.1%) and B (wt.0.02%) can be developed to get an yield strength of 451.25 MPa, Ultimate tensile strength of 669.57 MPa, % elongation 25.18 and Creep resistance at 1000 hours work life of 309 MPa to get better strength properties. [ABSTRACT FROM AUTHOR]

Purpose: The aerospace, energy and automotive industries have seen wide use of composite materials because of their excellent mechanical properties, along with the benefit of weight reduction savings. As such, the purpose of this study is to provide an understanding of the mechanical performance of these materials under extreme operational conditions characteristic of in-service environments. Design/methodology/approach: This study is novel in that it has evaluated the tensile performance and fracture response of additively manufactured continuous carbon fiber embedded in an onyx matrix (i.e. nylon with chopped carbon fiber) at cryogenic and room temperatures, for specimens manufactured with an angle between the specimen lying plane and the working build plane of 0°, 45° and 90°. Findings: Research findings reveal enhanced tensile properties (i.e. ultimate tensile strength and modulus of elasticity) by the 0° (X) built specimens, as compared with the 45° (XZ45) and 90° (Z) built specimens at cryogenic temperature. A reduction in ductility is observed at cryogenic temperature for all build orientations. Fractographic analysis reveals the presence of fiber pullout/elongation, pores within the onyx matrix and chopped carbon fiber near fracture zone of the onyx matrix. Research limitations/implications: Research findings present tensile properties (i.e. ultimate tensile strength, modulus of elasticity and elongation%) for three-dimensional (3D)-printed onyx with and without reinforcing continuous carbon fiber composites at cryogenic and room temperatures. Reinforcement of continuous carbon fibers and reduction to cryogenic temperatures appears to result, in general, in an increase in the tensile strength and modulus of elasticity, with a reduction in elongation% as compared with the onyx matrix tensile performance reported at room temperature. Fracture analysis reveals continuous carbon fiber pull out for onyx–carbon fiber samples tested at room temperature and cryogenic temperatures, suggesting weak onyx matrix–continuous carbon fiber adhesion. Originality/value: To the best of the authors' knowledge, this study is the first study to report on the cryogenic tensile properties and fracture response exhibited by 3D-printed onyx–continuous carbon fiber composites. Evaluating the viability of common commercial 3D printing techniques in producing composite parts to withstand cryogenic temperatures is of critical import, for aerospace applications. [ABSTRACT FROM AUTHOR]

In this paper, the hardness, ultimate tensile strength, yield strength, elongation E100, S−N curves, and fatigue performance of 7075 aluminum alloy were obtained after aged at 170 °C for different times (10 h, 15 h, and 20 h). Additionally, the microstructure and fatigue fracture of the alloy were observed. The investigation results show that as the forming time increased, the hardness, ultimate tensile strength, and yield strength decreased, the elongation first decreased, then increased, and the fatigue limit increased. As the forming time increased, the metastable phase gradually transformed into a steady phase and coarsened, the width of precipitate free zone increased, and the width of the fatigue strip decreased. After creep age forming for 20 h, the precipitate free zone was the widest, approximately 100 nm. [ABSTRACT FROM AUTHOR]

The heterostructured medium Mn steels with different volume fractions of heterostructure are fabricated via partially austenite reversed transformation (PART), and the influence of morphological parameter on the mechanical properties of the investigated steel is discussed. The PART samples exhibit the enhanced yield strength and ultimate tensile strength without sacrificing the ductility in comparison with their homogeneous counterpart. The double heterogeneities of microstructure and composition are found in the PART samples, which should be responsible for the enhancement in the mechanical properties. The yield strength and the ultimate tensile strength of the PART samples decrease with the increasing holding time at the partially austenized temperature, which is associated with the enhanced grain size and the elevated volume fraction of the lath-type microstructure. [ABSTRACT FROM AUTHOR]

This study focuses on the synthesis of a Zn-Al alloy nanocomposite, incorporating varying weight percentages (2, 4, 6, and 8 wt.%) of SiC nanoparticles with an average size of 30 nm. The preparation was carried out using the stir casting technique. Experimental tests, including hardness, compression, and tensile tests, were conducted on both the Zn-Al alloy and its composite. Furthermore, the surface morphology of the materials was examined using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The mechanical properties and microstructure of the composite samples were assessed. The results indicate that an increase in the weight percentage of SiC nanoparticles led to corresponding increases in hardness, compression strength, and ultimate tensile strength of the composite materials. When compared to an unreinforced alloy, nanocomposites reinforced with 2, 4, 6, and 8 wt.% SiC nanoparticles exhibited hardness improvements of 9.1%, 15%, 20.8%, and 30% respectively, as well as increases in ultimate tensile strength of 2.56%, 4.46%, 7.74%, and 12.21%, and compression strength enhancements of 17.5%, 20%, 22.4%, and 31.5% respectively. Notably, the composite sample containing 8% weight of reinforcement consistently demonstrated the highest ratings in terms of hardness, tensile strength, and compression strength. Based on the scanning electron microscopy (SEM) results, the nanocomposite alloy exhibits a dendritic morphology, with evenly distributed silicon carbide (SiC) particles embedded within the metal matrix. Furthermore, the interface between the SiC particles and the metal matrix demonstrates a strong bond. As a consequence, the mechanical properties of the fabricated composites were significantly improved. [ABSTRACT FROM AUTHOR]

Purpose: In binder jetting, the interaction between the liquid binder droplets and the powder particles defines the shape of the printed primitives. The purpose of this study is to explore the interaction of the relative size of powder particles and binder droplets and the subsequent effects on macro-scale part properties. Design/methodology/approach: The effects of different particle size distribution (5–25 µm and 15–45 µm) of stainless steel 316 L powders and droplet sizes (10 and 30 pL) on part density, shrinkage, mechanical strength, pore morphology and distribution are investigated. Experimental samples were fabricated in two different layer thicknesses (50 and 100 µm). Findings: While 15–45 µm samples demonstrated higher green density (53.10 ± 0.25%) than 5–25 µm samples (50.31 ± 1.06%), higher sintered densities were achieved in 5–25 µm samples (70.60 ± 6.18%) compared to 15–45 µm samples (65.23 ± 3.24%). Samples of 5–25 µm also demonstrated superior ultimate tensile strength (94.66 ± 25.92 MPa) compared to 15–45 µm samples (39.34 ± 7.33 MPa). Droplet size effects were found to be negligible on both green and sintered densities; however, specimens printed with 10-pL droplets had higher ultimate tensile strength (79.70 ± 42.31 MPa) compared to those made from 30-pL droplets (54.29 ± 23.35 MPa). Originality/value: To the best of the authors' knowledge, this paper details the first report of the combined effects of different particle size distribution with different binder droplet sizes on the part macro-scale properties. The results can inform appropriate process parameters to achieve desired final part properties. [ABSTRACT FROM AUTHOR]

Eight commercial austenitic stainless steels were tensile tested in reference atmosphere, in gaseous high-pressure hydrogen and in gaseous hydrogen precharged condition using conventional (CS) and tubular specimens (TS). For all configurations, 0.2 yield strength and ultimate tensile strength were comparable. In reference atmosphere, reduction of area of CS was higher compared to TS, whereas in gaseous high pressure hydrogen reduction of area of CS was lower compared to TS. In gaseous hydrogen precharged condition reduction of area of CS and TS were comparable for the severely affected grades. The differences in necking behavior between CS and TS are explained by different competitions between necking and hydrogen assisted crack initiation and growth especially for the tests in high pressure hydrogen gas. • Eight commercial austenitic stainless steels were tensile tested using conventional (CS) and tubular specimens (TS). • Tests were performed in gaseous high-pressure hydrogen and in gaseous hydrogen precharged condition. • For all configurations, 0.2 yield strength and ultimate tensile strength were comparable. • In reference atmosphere, reduction of area of CS was higher compared to TS. • In gaseous high-pressure hydrogen, the reduction of area of CS was lower compared to TS. [ABSTRACT FROM AUTHOR]

To study the effects of Fe content and cold drawing strain on the microstructure and properties, Cu-Fe alloys were prepared via powder metallurgy and hot extrusion. Scanning electron microscopy was applied to observe the Fe phase, and the ultimate tensile strength was investigated using a universal material testing machine. Alloying with an Fe content below 10 wt.% formed a spherically dispersed Fe phase via the conventional nucleation and growth mechanism, whereas a higher Fe content formed a water-droplet-like Fe phase via the spinodal decomposition mechanism in the as-extruded Cu-Fe alloy. Further cold drawing induced the fiber structure of the Fe phase (fiber strengthening), which could not be destroyed by subsequent annealing. As the Fe content increased, the strength increased but the electrical conductivity decreased; as the cold drawing strain increased, both the strength and the electrical conductivity roughly increased, but the elongation roughly decreased. After thermal–mechanical processing, the electrical conductivity and strength of the Cu-40Fe alloy could reach 51% IACS and 1.14 GPa, respectively. This study can provide insight into the design of high-performance Cu-Fe alloys by tailoring the size and morphology of the Fe phase. [ABSTRACT FROM AUTHOR]

Magnesium alloys are still attractive materials for applications that necessitate light weight due to their low density, moderate strength, and good corrosion resistance. AZ91 is one of the widely applied magnesium alloys due to its very good castability and strength. However, one of the drawbacks of magnesium alloys is the low elastic modulus. So, reinforcing AZ91 with carbon short fibers with the aim of further increasing the strength and improving the elastic modulus is investigated in this study. Squeeze cast AZ91-23 vol.% carbon short carbon (AZ91-C) and the unreinforced AZ91 are deeply examined by tensile testing at different temperatures (20, 100, 150, 200, 250, and 300 °C). Tensile stress–strain curves are measured and the tensile parameters (yield stress, ultimate tensile strength and strain) are defined and presented against the test temperature. Yield stress of AZ91 at 20 °C (109 MPa) is doubled (226 MPa) in the reinforced AZ91-C. Yield stress is found to slightly decrease with increasing the test temperature. Ultimate tensile strength of AZ91 at 20 °C (198 MPa) is increased (262 MPa) in the reinforced AZ91-C. The improvement of the ultimate tensile strength due to reinforcing increases with increasing the test temperature. Flow curves are determined and described by a modified Mecking–Kocks relationship and the flow parameters are determined and described as a function of the test temperature. Microstructure investigation was undertaken of the fractured tensile specimens at the grain boundaries rich in eutectic structure formed at the grain boundaries. Mixed brittle/ductile fracture mode is detected on the fracture surface of unreinforced AZ91, while the SEM investigations show matrix/carbon fiber detachment and fiber fracture as main fracture modes. [ABSTRACT FROM AUTHOR]