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The aim of this paper is to study the mechanical behavior of corrugated board boxes, focusing attention on the strength that the boxes are able to offer in compression under stacking conditions. A preliminary design of the corrugated cardboard structures starting from the definition of each individual layer, namely the outer liners and the innermost flute, was carried out. For this purpose, three distinct types of corrugated board structures that include flutes with different characteristics, namely the high wave (C), the medium wave (B), and even the micro-wave (E), were comparatively evaluated. More specifically, the comparison is able to show the potential of the micro-wave which would eventually allow a significant saving of cellulose in the fabrication process of the boxes, thus reducing the manufacturing costs and causing a lower environmental footprint. First, experimental tests were carried out to determine the mechanical properties of the different layers of the corrugated board structures. Tensile tests were performed on samples extracted from the paper reels used as base material for the manufacturing of the liners and flutes. Instead, the edge crush test (ECT) and box compression test (BCT) were directly performed on the corrugated cardboard structures. Secondly, a parametric finite element (FE) model to allow, on a comparative basis, the study of the mechanical response of the three different types of corrugated cardboard structures was developed. Lastly, a comparison between the available experimental results and the outputs of the FE model was carried out, with the same model being also adapted to evaluate additional structures where the E micro-wave was usefully combined with the B or C wave in a double-wave configuration. [ABSTRACT FROM AUTHOR]

The research undertaken for this paper was inspired by the results of theoretical analyzes and strong experimental evidence confirming the possibility to induce the phenomenon of viscous flow (typical for liquids) in the process of low-temperature KOBO extrusion of metals. Thus, despite the constant solid state of the metal, the KOBO plastic deformation process requires much lower stress (low flow resistance) in comparison with conventional extrusion. On the other hand, the KOBO method is particularly attractive due to the generation of high strength properties in the product/extrudate favorable for low (room) temperature deformation as well as superplastic features at higher temperature ranges. This paper presents the results of the studies on the efficiency of low-temperature KOBO extrusion of hardly-deformable materials in massive form (Mg4Li, AK11, Cu6.5P) and fragmented fractions (2014, 7075, AZ91, titanium grade 2). Particular attention was paid to the structure and mechanical properties of the obtained extrudates, which were rated as exceedingly favorable. As such, the paper provides new technological arguments for the application of the KOBO method in plastic deformation of materials as it guarantees their functional properties. [ABSTRACT FROM AUTHOR]

This paper aims to explore the influence of surface curvature distribution on the mechanical properties of lattice structures. In this study, a series of typical structure types were designed to obtain lattice structures with different surface Gaussian curvatures, including BCC (body center cubic) configuration, cross-cube configuration, and diamond lattice structure. Then, the above-mentioned porous structural sample was formed by SLM (selective laser melting), and the relevant mechanical properties were obtained by simulation and experiment. In addition, a characteristic method to describe the surface curvature of discrete triangular plaques is proposed and used to calculate the curvature distribution of the designed lattice structure. The results show that the lattice structure with concentrated Gaussian curvature distribution on the surface has good mechanical properties. Especially, for the cross-cube structure, the elastic modulus of the traditional configuration lattice structure increases by 79%, and the elastic modulus of the stretched structure increases by 70% when the volume fraction increased from 10 to 15%. Meanwhile, the elastic modulus for the traditional structure and the stretched structure increases by 41% and 14%, respectively, when the volume fraction of the structure increases from 15 to 20%. It is noted that the influence of surface curvature distribution on mechanical properties is slightly inferior to the volume fraction, which provides a new idea for the quantitative evaluation and design of porous structural properties. In addition, the BCC structure with concentrated curvature distribution provides a new scheme for the protection device after the stress climb stage after the elastic stage. Furthermore, the influence of surface curvature on the mechanical properties of lattice structures described in this paper will provide new inspiration for lattice structures in the fields of biocompatibility and heat exchange. [ABSTRACT FROM AUTHOR]

Steel-aluminum dissimilar metal welding has a robust application demand in automobile lightweight. However, the formation of Fe-Al intermetallic compounds (IMCs) reduces the steel-aluminum welded joint's mechanical properties (tensile strength or linear load). This paper reviews the research results of transition layer and filler wire in improving the mechanical properties of steel-aluminum laser welding joint (SALWD). The mechanism of improving the mechanical properties of SALWD by filler wire and transition layer is summarized. The transition layer's development direction uses multi-element, trace rare earth elements and high-strength fiber. The development direction of filler wire is to develop the low melting point, good wettability, and high-strength filler wire. This article has reference value for researching dissimilar metal welding and transition layer and welding wire materials. [ABSTRACT FROM AUTHOR]

Laser powder bed fusion (LPBF) is a rapid prototyping technology with high forming accuracy, which can print complex metallic components applied in the aerospace field. The aluminum alloy parts manufactured by LPBF can better achieve lightweight structures than other metallic materials due to the combination of materials and structure. However, many metallurgical defects such as spherification, porosity, coarse grain, and crack are more likely formed inside the printed components during the LPBF process, resulting in the decline of properties of the aluminum alloy. In order to solve the above-mentioned problems, researchers have conducted in-depth exploration to improve the mechanical properties of LPBF fabricated Al parts. In this paper, the methods to improve the forming quality of aluminum alloy are explored from the direction of regulation strategies for microstructure and properties. The current research status of LPBF-processed aluminum alloy is discussed from the aspects of process parameter optimization, alloying element modification, reinforcing phase addition, and post-treatment. Furthermore, the microstructure and properties of LPBF-processed aluminum alloy are systematically reviewed. [ABSTRACT FROM AUTHOR]

This paper investigates the mechanical properties of AA2024 joints welded using the Friction Stir Welding (FSW) process, with a particular focus on comparing joints made with and without the inclusion of a commercially pure copper sheet between the edges being welded. The study aims to understand the influence of weld heterogeneity on the mechanical properties of FSW joints. Various joints were fabricated with a copper interlayer, and optimal process parameters—rotational speed, advancing feed, and tool geometry—were identified. Mechanical tests, including Rockwell B and Vickers hardness (HV) tests, as well as tensile tests, were conducted on both homogeneous and heterogeneous joints. The results showed that the presence of copper significantly affected the hardness distribution, particularly in the weld nugget. Heterogeneous joints demonstrated a notable increase in HV at the nugget and a reduced weld-affected area on both the advancing and retreating sides. The study found a strong correlation between process parameters, tool geometry, and the Ultimate Tensile Strength of the joints. Optimal mechanical properties were achieved in heterogeneous joints welded at 800 rpm and 40 mm/min with an 18 mm tool, resulting in a joint efficiency of 73%. These parameters differed significantly from those optimized for homogeneous joints, which were 1200 rpm and 100 mm/min with a 16 mm tool. It was also observed that exceeding 1000 rpm in rotational speed and 70 mm/min in feed speed is not advisable for heterogeneous welds. Future research should explore varying amount of copper and other materials, as well as different interposition methods, to further understand their effects on the mechanical properties of FSW joints. [ABSTRACT FROM AUTHOR]

Stainless steel clad plates have been gradually applied in the areas required for both good mechanical properties and corrosion resistance effects, but welding technology is still playing a limiting role in its further large-scale application. The aim of this paper is to review the welding status and future prospective of stainless steel clad plates so as to offer a basis for following research. The paper carefully discussed the welding issues of stainless steel clad plates from three aspects of conventional multi-layer and multi-pass welding, high efficiency welding, and welding finite element simulation, respectively. And simultaneously, the relevant future works were planned too. [ABSTRACT FROM AUTHOR]

The advent of additive manufacturing technologies significantly encouraged the development and usage of lattice structures. This paper aims to experimentally investigate the influence of dimension, building position, and orientation on the mechanical properties of Ti6Al4V trusses, manufactured by electron beam melting process, to be used in lattice cells. Specimens were manufactured considering the following parameters: truss diameter (1, 1.5, 2 mm), growth orientation (0°, 45°, 90°), and specimen position inside the building chamber. Trusses with diameter of 1 mm showed inconsistent mechanical properties caused by the poor manufacturing quality. Specimen position was found to influence the analyzed mechanical properties. Unmelted powders were observed to affect the outer surfaces of all specimens and the whole cross-sections of specimens manufactured at 0°. Specimens manufactured at 45° with diameter of 2 mm demonstrated the best performances, whereas specimens manufactured at 90° with diameter of 2 mm displayed the highest elongation at fracture. [ABSTRACT FROM AUTHOR]

Particle reinforced iron matrix composite (PRFMC) have attracted widespread attention because of their good physical and mechanical properties. In this paper, the preparation technology of PRFMC, the influence of particles on the mechanical properties of iron matrix composites (FMC) and the reinforcement mechanism are systematically reviewed. The results show that the preparation technology has a significant impact on the physical and mechanical properties of PRFMC. The defects in the traditional preparation technology are improved in the new preparation technology. The addition of reinforcing particles has a great influence on the mechanical properties of FMC, and the strengthening effect varies according to different reinforcing particles. The reinforcing mechanism of PRFMC mainly includes microstructure strengthening and micromechanical strengthening. [ABSTRACT FROM AUTHOR]

Inconel718 maintains excellent mechanical properties at high temperatures of 700 ℃ and has a wide range of applications in aerospace, high-performance turbines, and other fields. However, the use of improper laser process parameters makes the Inconel718 obtained by the directional energy deposition method have poor performance and defects, and there are currently fewer studies on the regulation of the mechanical properties of the preparation of Inconel718 by directed energy deposition. In this paper, the influencing regulation of laser process parameters of laser power, scanning speed, hatch spacing, layer thickness, and forming direction on the microstructure and mechanical properties of Inconel718 prepared by directional energy deposition is investigated by single-factor test method. The mechanical properties of Inconel718 obtained by directional energy deposition and forge are compared. The results show that, among the five laser process parameters, the laser power and forming direction have significant effect on the mechanical properties of Inconel718 obtained by directional energy deposition, while the scanning speed, scanning spacing, and layer thickness have less influence on its mechanical properties. Compared with Inconel718 prepared by ordinary forge, the tensile strength of Inconel718 obtained by directed energy deposition is reduced by 7.64%, the hardness is increased by 23.55%, the impact strength is reduced by 17.6%, and the plasticity is reduced obviously. Good mechanical properties can be reached from the Inconel718 obtained by the directional energy deposition method. [ABSTRACT FROM AUTHOR]

In this paper, a disk laser welding was developed to join 3-mm thin-Sect. 30Cr3 ultra-high-strength steel which was widely used in aerospace. The microstructure and mechanical properties of welded joint were investigated in detail. The results indicated that the recommended laser linear energy range were between 150 and 165 J/mm to guarantee that the melting width was up to 1 mm as well as less oxidation, spatter, and depression on the weld. Meanwhile, for the as-welded (AW) condition, the base metal (BM) consisted of ferrite matrix with distributing small spherical carbides, also known as spherical pearlite. While, the fine grained region, coarse grained region, and weld metal were all composed of martensite. However, the partially transformed region mainly consisted martensite with a little of spherical pearlite. Meanwhile, the average grain sizes of weld metal, HAZ, and base metal were 1.3 μm, 1.5 μm, and 1.8 μm, respectively. However, for the post-weld heat treatment (PWHT) condition, the whole welded joint was all composed of tempered martensite, and the average grain size of welded joint was about 1.7 μm. The tensile strength of the welded joint was higher than that of the base metal both in the AW and PWHT condition as all the fracture with shrinkage occurred in the BM of the specimens. Additionally, the average yield strength of the AW and PWHT are about 600 MPa and 1700 MPa, respectively. [ABSTRACT FROM AUTHOR]

Ultrasonic-assisted electrolytic in-process dressing (ELID) grinding can be used in the high-efficiency and high-precision machining of difficult-to-process materials. This paper establishes a prediction model of oxide film thickness growth. We conducted ultrasonic-vibration-assisted experiments on an electrolytic cast-iron-bonded grinding wheel and carried out high-speed steel ball friction and wear tests. The mechanical properties and surface morphology of the oxide film were characterized by nanoindentation, SEM, and three-dimensional morphology. The relative error between the theoretical model and the measured data did not exceed 7%. With the increase in oxide film thickness, the oxide film on the surface of the cast-iron-bonded grinding wheel became looser, the film surface exhibited more defects, and the hardness and elastic modulus of the oxide film were far lower than those of the cast-iron-bonded grinding wheel substrate. The adhesion of the oxide film first increased and then decreased with the increase in film thickness; the complete peeling distance increased with the increase in film thickness. The thicker the oxide film was, the more likely it was to fracture and fall off, the larger the average coefficient of friction (COF), the higher the wear rate of the cast-iron-bonded grinding wheel, and the lower the cast-iron-bonded grinding wheel's service life. [ABSTRACT FROM AUTHOR]

3D printing, specifically fused deposition modeling (FDM) of poly-ether-ether-ketone (PEEK), is one of the most powerful and efficient state-of-the-art manufacturing techniques. However, FDM of PEEK is challenging. Indeed, it is critical to consider specific 3D printing parameters and filament feedstock quality to achieve optimum mechanical properties in the 3D-printed PEEK parts. In this paper, we investigate the effect of specific 3D printing parameters such as nozzle and chamber temperature, print speed, and layer height on the mechanical properties of 3D-printed PEEK. Moreover, we explore the effect of filament quality on the structures' mechanical properties. In that regard, we developed PEEK filaments using a customized extruder setup in-house and used those laboratory-developed filaments (LD) to 3D print PEEK structures suitable for mechanical testing (tensile, compression, and flexural testing) and compared them to the mechanical properties of 3D-printed parts that were developed using commercially available (CA) filaments. Results indicate that an optimum combination of a nozzle and chamber temperature, print speed, and layer height is appropriate to achieve 3D-printed parts with optimum mechanical properties. Notably, results confirmed no significant differences between the specimen groups developed using LD and CA filaments, highlighting that the LD filaments were of comparable quality to the CA ones. The highest mean strengths recorded for the parts printed with the LD filaments were 106.45 MPa (compressive), 85.43 MPa (tensile), and 102.63 MPa (flexural). This paper confirms that high-quality PEEK-based filaments can be developed in-house to yield 3D-printed PEEK parts with optimum mechanical properties. [ABSTRACT FROM AUTHOR]

PolyJet technology is one of the additive manufacturing technologies, which can produce complex geometries with variety of textures. The 3D printed complex geometry parts need better mechanical behaviour. The mechanical properties of a fabricated product depend on several process parameters such as build orientation, layer thickness, material and surface finish. This paper aims to study the effect of printing mode and type of surface finish on the mechanical properties of VeroBlue material used in PolyJet technology. The tensile, flexural and shore hardness tests are carried out to determine the mechanical response of the fabricated specimen. Four different combinations are derived from printing mode (high quality (HQ) and high speed (HS)) and finish type (matte (M) and glossy (G)). Findings indicate the HS-G specimens have better mechanical property and are faster in production and cheaper than HQ-M, HQ-G and HS-M. Highest average tensile strength of the HS-G (49.77 MPa) is deviated by 11.19% from standard value. Tensile specimens of HS-G save 60.86% of printing time and 14.72% of cost than HQ-G. This research paper provides a unique way of meeting optimal selection process parameters. Finally, a case study was carried out for the selected application with optimized process parameters. [ABSTRACT FROM AUTHOR]

Lightweight bent aluminum profiles are widely utilized in transportation fields. In this paper, the torsional channel self-bending extrusion process (TCSE) was adopted to machine AA6063 bent aluminum profiles in a single operation to verify the process's feasibility. Effects of extrusion parameters on the curvature, microstructure, and mechanical properties of the profiles were researched, and the extrusion process was simulated. The results show that the extruded profiles had good curvature stability. The grains were equiaxed in the cross longitudinal section, and the grain size at the outside diameter (OD) position was smaller than the inside diameter (ID) position. When the difference in deformation temperature at the OD edge was above 31 K, a smaller peripheral coarse grain (PCG) layer was formed at the OD edge with a thickness of about 400 μm, resulting in reduced hardness. The Mg2Si particles served as the main strengthening phase, which increased in number and decreased in size with increasing billet temperature and extrusion speed. Increasing the billet temperature and speed improved the mechanical properties of the material, with an increase in average hardness of 55.9% and 19.5%, and ultimate tensile strength (UTS) of 12.5% and 7.1%, respectively. By comprehensively considering the factors of extrusion load, microstructure, and mechanical properties, the optimum bent profile for different curvatures was determined. When a large curvature (≥328.67 mm) was required, it was preferred to increase the billet temperature. When a smaller curvature (≤328.67 mm) was required, it was advisable to increase extrusion speed. [ABSTRACT FROM AUTHOR]

Shear thickening fluid (STF), a type of non-Newtonian fluid, becomes more viscous as the strain rate rises. Due to their unique rheological properties, STFs have outstanding vibration-damping and energy-absorbing capabilities and have tremendous engineering applications. To obtain a comprehensive understanding of STFs, a review of aspects from the principle and composition, theoretical expression to application of STFs is presented on what are in this paper. In terms of principle of STFs, the thickening theory and thickening mechanism are explained firstly. The rheological characteristics and mechanical properties of STFs are reviewed. Subsequently, typical composition and preparation methods of STFs are enumerated. In terms of theoretical expression, theoretical modelling methods towards the viscosity of STFs are summarized. In terms of application, influencing factors on the thickening properties are examined. Furthermore, current engineering applications of STFs are presented. Finally, future perspectives on the research of STFs are put forward in the conclusion. The work of this article provides a systematic study and thorough knowledge of STFs, which is beneficial for numerous potential engineering applications of STFs. [ABSTRACT FROM AUTHOR]

The mechanical properties of welded joints are heterogeneous, which result in complicated stress distribution in welded structures subjected to external loads. An accurate description of heterogeneous weld properties may facilitate the prediction of stress evolution and damage development in welded structures. The heterogeneous mechanical properties of thick welded joints are difficult to be measured directly because the stress–strain data obtained by tensile tests only represent the average properties of the specimen. In this paper, a two-dimensional flow stress model that varies in the transverse and thickness directions is proposed to calculate the heterogeneous mechanical properties of thick welded joints. The boundaries of the welding zones in the friction stir welded joints are clarified by using metallographic analysis. The microhardness tests are performed to reveal the variation of flow stress in the transverse and thickness directions. A force equilibrium equation is established to determine the flow stress functions in different welding zones. The two-dimensional flow stress model is implemented into finite element analysis to predict the mechanical behaviors of thick welded joints. The results show that the stress–strain relations and strain fields predicted by the two-dimensional flow stress model are in good agreement with experimental ones. The strain hardening behaviors of the welded joints are different in the thickness direction, and the maximum strain is concentrated on the thermo-mechanically affected zone and the heat affected zone. The proposed model may be used to predict the complex mechanical behaviors of thick welded joints. [ABSTRACT FROM AUTHOR]

TiAl-based alloys represent a novel class of lightweight, high-temperature structural materials that exhibit exceptional properties, including low densities, high specific strength, and remarkable thermal resistance. These properties make them exceedingly promising for supplanting nickel-based superalloy in the production of pivotal components for aerospace, marine, and automotive engines. Regrettably, like most intermetallic compounds, TiAl-based alloys are subject to certain shortcomings, such as room-temperature brittleness, deformation difficulties, and susceptibility to cracking, which present challenges for shaping these materials into intricate forms using traditional processing methods. In this regard, additive manufacturing (AM), with its high processing freedom and energy, has emerged as a revolutionary technology for the fabrication of complex structural components of TiAl-based alloys. However, AM TiAl-based alloys are still plagued by issues such as cracking, porosity, and uneven microstructure. Therefore, various post-processing techniques were employed to tune the microstructure, and thus enhance the performance of AM TiAl-based alloys. This paper reviews the research progress of AM TiAl-based alloys, summarizing the effects of process parameters, alloying, heat treatment, and surface treatment on the microstructure and mechanical properties of these alloys. Additionally, it discusses the challenges and prospects for the future development of AM TiAl-based alloys. [ABSTRACT FROM AUTHOR]

The self-piercing riveting is a major mechanical joining technique to join dissimilar lightweight materials, which has been widely used in the automotive industry. However, the die-casting aluminum sheet under the self-piercing riveted joint will generate cracks on the joint button due to the low ductility of the die-casting aluminum. A new technique of local-thickened self-piercing riveting (LT-SPR) is proposed to solve the problem of cracking on joint buttons in this paper. The effect of process parameters on cracking on joint button are discussed systematically and experimentally. The joint quality, mechanical properties, and failure mode of the LT-SPR joints are studied compared to the conventional SPR (C-SPR) joints. It is concluded that crack-free joints can be obtained in a wide range of rivet-die combinations using LT-SPR. Compared with the C-SPR joints, LT-SPR joints have larger forming quality indexes, smaller riveting force, smaller bending deformation, and better mechanical properties. For the LT-SPR process, the mechanical properties and failure mode are highly dependent on the rivet length, and larger rivet length can cause rivet fracture failure in the LT-SPR. The energy absorption of the joints that failed in interlock failure is superior to that of joints with rivet fracture failure, and joint strength is not affected by rivet fracture failure. [ABSTRACT FROM AUTHOR]

Composite materials are very attracting in both aerospace and automotive applications because of their exceptional strength, stiffness-to-density ratio, and superior physical properties. However, these materials are susceptible to damage, necessitating effective repair techniques to maintain their structural integrity and extend their operational life. Due to the high production costs for every single component in carbo-resin, further repair techniques have been developed to repair damaged components of a complex structure on site without having to disassemble any element. In this scenario, the scope of this research paper is to implement an innovative repair procedure to be carried out on-site. The hot bonding process was used for the scope, and two different technologies involving both the prepreg and the dry patches impregned on site (infused) were proposed. Firstly, the composite panels were manufactured, and then they were analysed through non destroying evaluation techniques. The mechanical behaviour of the samples (under both the pristine and the repaired conditions) was evaluated through open hole tensile and compression tests aiming to assess their properties under maximum stress conditions. Impact tests at penetration and at indentation were conducted to study the performances under dynamic loading. Despite an increase of voids percentage was proved for the dry patches impregned panels (+ 33%), better mechanical properties were found for the infused specimens compared to prepregs (+ 8% and + 10% under compression and tensile loads, respectively), proving the effectiveness of the developed process. [ABSTRACT FROM AUTHOR]

This paper investigates the cold spray additive manufacturing of a thick wall made of pure Al powder with a granulometry of + 45–15 μm with a size d50 = 26.95 µm. A high wall with vertical lateral faces is obtained without clogging, using a compensation building strategy and gas pressurization at 30 bars, 400°C. Layer by layer, using a suitable set of deposition parameters, the profile of the deposit grows without a lack of material at the lateral edges and then produces the near-net shape 3D wall. However, a structural characterization shows an issue of pore development and low mechanical properties. A porosity with a typical pore size range of 6–100 µm is observed from the bottom zone to the top zone of the wall, with a random occurrence and with a fraction of pores up to 8%. The distribution of the pore size shows a high fraction of fine pores (6–10 µm) up to ~ 70%. There can be a weak fraction (~ 0.04%) of larger pores (130–200 µm) and such pores appear as a continuous connexion of pores within the deposit due to a bad stacking and a bad bonding of particles during the additive growth. These detrimental defects ease the brittle mechanical behaviour of the wall during a tensile test. An intergranular-like fracture is observed with some trace of dimples but the brittle stress/strain curve until rupture suggests a predominant failure by cleavage due to the porosity. The fracture strain is less than 2%. The ultimate tensile strength and the elastic modulus are limited to about 50 MPa and about 50 GPa, respectively. [ABSTRACT FROM AUTHOR]

The service performance of hot stamped ultra-high strength steel after die punching was evaluated in this paper through typical experiments, including tensile tests, bending tests, and hydrogen embrittlement tests, as well as characterization analysis. The tested samples were prepared through a specially designed tool by considering different die clearances, punch corner radii, and punch shapes. The results showed that the tensile properties are closely related with the selected punching parameters, while the bending properties and hydrogen embrittlement susceptibility are less sensitive to parameters. Furthermore, the laser cutting method was also involved to produce holes on hot stamped parts and compared with the punching samples. It was found that the laser cutting samples performed better in terms of tensile properties and hydrogen embrittlement susceptibility, which were due to the effects of annealing treatment during laser cutting that decreases the material hardness and brings compressive residual stress near the cutting surface, while the bending properties are insensitive to different drilling methods. [ABSTRACT FROM AUTHOR]

Laser cladding has significant advantages in the forming process of Invar alloy. Nevertheless, the coefficient of thermal expansion, microstructure and mechanical properties still need to be further investigated. In this paper, the Invar alloy powder was used to prepare cladding samples, and the performance and microstructure of the cladding layer were investigated. The mechanical and thermal expansion performances of the cladding layer were analysed using a universal material testing machine and a thermal expansion instrument, and the microscopic structure and micro zone composition of the tensile fracture of the cladding layer were investigated using an SEM scanning electron microscope and an EDS energy spectrum analyser. The results show that the mechanical properties of the Invar alloy transverse cladding layer are better than those of longitudinal cladding layer; the thermal expansion performance of the cladding layer is good, and it keeps the same with the base material in the range of 25–200 °C; the fracture analysis reveals more dimples in the transverse cladding layer fracture with better plastic tenacity, and intergranular fracture and quasi-cleavage fracture in the longitudinal cladding layer fracture with slightly poor plastic tenacity. [ABSTRACT FROM AUTHOR]

This paper completes the welding of 4-mm-pure copper with bobbin tool-friction stir welding technology for the first time, and we discovered the evolution of microstructure by combining the temperature field evolution, microstructure, mechanical properties, electrical properties, and chemical corrosion resistance of welded joints. The findings demonstrate that the temperature field is dynamic, with the advancing side experiencing the highest peak temperature (422 °C). The size of recrystallized grain in the stir zone (SZ) is slightly larger than that of the base metal (BM), and the "banded structure" of alternating coarse-grain bands and fine grain bands is observed in this region. The microstructure of the heat-affected zone (HAZ) has larger grain size. Both the advancing and retreating sides of the thermomechanically affected zone (TMAZ) have a distinct microstructure, with the advancing side having a more pronounced elongated and curved microstructure. The welded joint has a specific microstructure gradient from the standpoint of the overall microstructure, which results in the fracture location at TMAZ with the biggest microstructure gradient in the tensile test, and the welded joint's efficiency is only 57.56% of the base metal. At the same time, the resistivity and the chemical corrosion resistance of the welded joint will decrease. During the welding process, the grains in the stir zone mainly undergo geometric dynamic recrystallization and the heat-affected zone mainly undergoes dynamic recovery. [ABSTRACT FROM AUTHOR]

Stainless steel (SS) alloys produced by laser-based powder bed fusion (LPBF) offers comparable and sometime superior mechanical properties compared to conventionally processed materials. Some of these steels have been extensively studied over the last decade; however additively manufactured martensitic SS, such as AISI 420, need further research in characterizing their post-built quality and mechanical behaviour. This lack of information on martensitic SS is not consistent with their growing demand in the automotive, medical and aerospace industries due to their good corrosion resistance, high hardness and good tensile properties. Selection of the appropriate process parameters and post treatments plays a fundamental role in determining final properties. For this reason, the effect of LPBF process parameters and different heat treatments on density, defect characteristics and locations, roughness and mechanical properties of AISI 420 were investigated in this paper. A first experimental campaign was carried out to establish a set of suitable process parameters for industrial applications. Starting from this result, detected defect properties were investigated by computed tomography (CT) scans. Dimensions, sphericity and distributions of defects inside the volume were analysed and compared between samples manufactured with different parameters. In the second part of the paper, the influence of process and post-process conditions on mechanical properties was investigated. The final presented results establish a correlation between the employed production cycle and the resulting properties of LPBF AISI 420 specimens. [ABSTRACT FROM AUTHOR]

This paper investigates the effects of hygrothermal aging on PA6 filaments used as raw material in fused filament fabrication (FFF). The filaments were subjected to various aging conditions to evaluate their physicochemical and thermomechanical properties. The results show that water was uniformly absorbed at all aging temperatures, although the kinetics of absorption varied. The introduction of water caused an increase in chain mobility, resulting in a decrease in the glass transition temperature, crystallinity, Young's modulus, tensile strength, and yield strength. These changes in properties followed a consistent trend, with an initial rapid decrease followed by stabilization at a minimum value common to all temperatures. Notably, elongation at break increased sevenfold at the highest temperature. Compared to samples printed with unaged filaments, those produced with aged filaments exhibited a decrease in mechanical properties. [ABSTRACT FROM AUTHOR]

Steel matrix composites are widely used in automotive, aerospace, wear, and cutting applications due to their superior mechanical properties, ease of manufacture, and low cost. However, there are still some limitations in the strength, reinforcement dispersion, and interface control of steel matrix composites, which are mainly achieved through different preparation processes and the addition of reinforced particles with mixed metal powders. Previous studies have demonstrated the enhanced ability of various reinforcing particles such as titanium carbide, silicon carbide, and alumina to enhance the wear performance of steel substrates, but there are still some challenges, such as uneven particle distribution, interface cracks, and unsatisfactory wettability. In this paper, the preparation methods of ceramic-reinforced metal matrix, ceramic reinforcement, steel matrix composition, microstructure, mechanical properties, and wear properties, as well as the parameters affecting their properties, are reviewed. The preparation processes of different ceramic-reinforced steel matrix composites are introduced, which are very suitable for overcoming challenges such as insufficient strength, poor dispersion, uneven distribution, and poor interfacial wettability. The influence of the morphology distribution and volume fraction of reinforcement on the wear rate of steel matrix composites was discussed. The importance of the microstructure of ceramic reinforcement in steel matrix and the interface between ceramic and matrix to improve the mechanical properties of steel matrix composites were emphasized. This review identifies the development trends in the field of research to fully illustrate the importance of more in-depth scientific research in steel matrix composites. [ABSTRACT FROM AUTHOR]

Wide applications of carbon fiber–reinforced polymer (CFRP) components in modern manufacturing enterprises have led to significant demand in the secondary machining processes. However, the machining surface quality characterization and its impact on the material's mechanical performance are not fully investigated. In this paper, a quantitative characterization method is proposed for assessing CFRP milling surface quality by combining SEM and image segmentation techniques, which was evaluated using three indices, namely, surface roughness, surface void fraction, and depth of affected zone. Finite element simulation and experiments about side milling of unidirectional CFRP with 90° fiber orientation were conducted to investigate the effects of milling conditions on the resulting surface quality indices. It was found that feed rate and cutting edge radius are two dominant factors that affect the surface void and the depth of affected zone, and the down-milling style is accompanied by greater machining damages due to the difference fiber cutting angle compared with up-milling. Meanwhile, the influence of the above three indices on the tensile and compressive strength of CFRP specimen was also obtained. It is concluded that the depth of the affected zone has a more significant effect on the strength degradation of machined CFRP materials. [ABSTRACT FROM AUTHOR]

The aim of this paper is to offer a novel friction stir welding technique to achieve non-thinning and lack of kissing bond welds with excellent mechanical properties. In the conventional friction stir welding (CFSW) process, a certain size spindle tilting angle and a shoulder plunge depth were applied in order to obtain high-quality welds. However, what was the reason for the thinning phenomenon of weld and thus the weakening of weld bearing capacity? The reduction of spindle tilting angle and shoulder plunge depth was likely to cause the welding tool not being able to reach the weld root, and thus, it was engendered for the kissing bond or the absence of complete penetration. In the present study, a novel welding tool with large size shoulder and Archimedes spiral groove was designed in order to achieve non-thinning and lack of kissing bond welds. The microstructures and mechanical properties of the joints obtained by the non-thinning and penetrating friction stir welding (NTPFSW) and the penetrating friction stir welding (PFSW) had been analyzed in detail. Compared with PFSW, NTPFSW had a narrow shoulder-affected zone. The thickness of NTPFSW joint is 0.1 mm thicker than that of BM and 0.22 mm thicker than that of PFSW joint. The stir zones (SZ) obtained by the PFSW and NTPFSW were both composed of fine equiaxed grains. The grains in the upper part of NTPFSW joint were larger in size, and the number of precipitates (θ' phase) was less. NTPFSW completely eliminated the weld thinning phenomenon, and the tensile properties were 365 Mpa, which is 2% higher than that of PFSW. [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]

AlSi12 has a high strength-to-weight ratio and good corrosion resistance properties. As a result, it has potential for use in the automotive and aerospace industries. However, AlSi12 is difficult to process using conventional manufacturing technologies because of its characteristics of having high thermal conductivity and reflectivity and flowability is low. It is necessary to explore how emerging manufacturing technologies can be used to effectively process it. Additive manufacturing (AM) offers great design freedom. For the AM of metallic parts, several technologies are in use, including selective laser melting (SLM), electron beam melting, laser engineered net shaping, and cold spray additive manufacturing. Among these AM processes, SLM technology is a cutting-edge manufacturing technique that has the potential to change the way people think about design and production. SLM of AlSi12 alloy presents unique advantages in producing components with high strength and low weight while having increased design freedom. However, there is a need for more information on how SLM can be effectively used to manufacture AlSi12 parts in a way that reduces defects without compromising the mechanical properties. Thus, this paper aims to review the factors that influence the mechanical properties of AlSi12 alloy printed parts produced using SLM. This information is useful in determining the factors that can be considered for manufacturing parts with outstanding characteristics. [ABSTRACT FROM AUTHOR]

The Al/Ti composite structure combines the performance advantages of these two materials and is widely used in aerospace. However, the physical and chemical properties of aluminum are quite different from those of titanium, resulting in poor joint quality when using conventional welding methods. Magnetic pulse welding (MPW), as an advanced solid-state welding, achieves metallurgical bonding by driving workpieces to collide at high speed with contactless force and is suitable for welding dissimilar materials or materials with poor weldability. So, the novelty of this paper is to apply magnetic pulse welding technology to join AA1060/TC4 sheets, and the purpose is to try to solve the problem of unsatisfactory welding effect of aluminum and titanium materials. In addition, an improved three-dimensional finite element model was developed to explore the electromagnetic mechanism and dynamic characteristics, which previous research has not systematically investigated. Meanwhile, the influence of process parameters on the welding effect of Al/Ti sheets was experimentally investigated and the quality of the joints was assessed by tensile test and microscopic observation. Ultimately, the experimental results show that the 1060 aluminum and TC4 titanium sheets can be effectively joined when the discharge energy reaches 10.08 kJ. Besides, the joint welded at 2 mm standoff distance has the maximum tensile strength of 1856.25 N and forms a defect-free wavy interface. It is demonstrated that MPW enables good welding of 1060 aluminum and TC4 titanium sheets, which lays a foundation for subsequent research. [ABSTRACT FROM AUTHOR]

The main objective of this research is to develop a characterization method for parts fabricated in metal powder bed fusion (PBF) processes, a type of additive manufacturing (AM) process. To characterize conventionally manufactured parts, many methods and standards are available, while no comprehensive standards or methods are available for AM parts. In this paper, a mechanical property characterization method is proposed that involves statistical analysis to select sample sizes and test coupon design considerations for metal printing, printing parameters, and applicability of existing testing standards for metal PBF, in addition to several mechanical properties. As proof of concept for the proposed characterization method, material and mechanical property characterization of the metal printed (EOS M280) EOS maraging steel grade 300 material is presented along with selected sample lots and relative errors. The characterization method presented in this paper is applicable to any metal AM process. [ABSTRACT FROM AUTHOR]

With the rapid development of industrial manufacturing, traditional WC–Co cemented carbides have exposed more and more problems. Therefore, the preparation of ultrafine/nanocrystalline-grained cemented carbides and the development of new binders have become a hot issue in the field of cemented carbides. Due to the unique design concept, the high-entropy alloys (HEA) binder not only has the unique properties of the HEA itself, but also can replace the traditional Co element as the binder of cemented carbide, which opens up the possibility for industrial manufacturing. The stable chemical properties of WC are coupled with the multi-principal element characteristics of HEA binder, which makes novel WC-HEA cemented carbides have the characteristics of grain refinement, compact structure, stable structure, and excellent capability. A multitude of studies have found that the new WC-HEA cemented carbide exhibits better service performance than WC–Co cemented carbide. In this paper, the main preparation processes of WC-HEA cemented carbide in recent years are summarized; the influence of the working principle, advantages, and defects of the two different preparation methods on the microstructure and properties of WC-HEA cemented carbide were described. The characteristics and influence mechanism of microstructure such as the composition of high-entropy alloy binder and the change behavior of phase structure of WC-HEA cemented carbide were discussed. The service performance characteristics of WC-HEA cemented carbides were discussed, including mechanical properties, wear resistance, oxidation resistance, and corrosion resistance. Finally, it summarizes the research challenges and prospects in the current research work, and provides an outlook on the research direction and application prospects of WC-HEA cemented carbide. [ABSTRACT FROM AUTHOR]

Hip implants face a significant challenge due to their limited lifespan, a concern amplified by the rising human life expectancy. Lattice structures have demonstrated the ability to provide precise control over geometry, thereby significantly enhancing implant performance. This paper introduces the development of graded additively manufactured Ti6Al4V lattice structures for orthopaedic implants. The objective focuses on developing a graded lattice unit cell design mirroring human bone properties, emphasising high surface curvature and design versatility to improve mechanical and biomedical properties, specifically osseointegration and stress shielding. The study involves modelling and grading simple cubic (SC) and body-centred cubic (BCC) lattice structures with various geometries and graded conditions and conducting compressive tests to identify the optimal configuration. The results showed that filleting was found to be the mechanical strength. On the other hand, BCC lattice structures demonstrated superior performance compared to SC structures. The optimised structure with a pore size of 400 µm provided an elastic modulus of 15.7 GPa, yield strength of 296 MPa and compressive strength of 530 MPa. This graded lattice design approach provides a promising technique for enhancing hip implant performance, offering potential improvements. [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 lattice structure based on minimal surface (also called the triply periodic minimal surfaces) is characterized by zero-value average curvature and high circulation, which leads to better mechanical performance than the CAD (computer aided design)-based structures. In this paper, the principle of least action was introduced to explain the extreme value phenomenon of minimal surface area, zero means curvature of the minimal surface, and the excellent mechanical properties. Firstly, a series of lattice structures with different configurations and the same volume fraction were fabricated by selective laser melting (SLM) with TC4 powder through changing the design method, including CAD design and minimal surface. Secondly, the solidworks software and the quasit-static compression are used to investigate the surface area of experimental samples, surface curvature, and compression responses. The results show that the zero-value mean curvature of the minimal surface follows the principle of least action. Also shown is that the minimal surface-based lattice structure has better mechanical properties than the CAD design method, which is attributed to the minimal surface that makes the nodes of the lattice structure smooth transition. The proposed concept is demonstrated through the comparison of the mechanical properties of representative specimens. The approach, which is generalized to the optimal design of lattice structures, provides a way toward functional gradient structures that need to simultaneously carry a load and achieve efficient heat dissipation or biocompatibility, such as load-bearing exchangers or bone implantation. [ABSTRACT FROM AUTHOR]

Ni-based superalloy GH4169 is widely demanded in the aerospace industry because of its excellent properties. However, the cutting of GH4169 at normal temperature has many challenges, such as tool wear, machining accuracy, and production efficiency. Cryogenic cutting has been an advanced method in assisting material removal machining. This paper focused on the cryogenic cutting performance of GH4169 at different initial temperatures, namely, 20 °C, −30 °C, −80 °C, and –130 °C. Firstly, the cryogenic mechanical properties of GH4169 were obtained by the Hopkinson pressure bar test at speed of 12 m/s and 18 m/s. The obtained data was used to analyze the cryogenic cutting performance of GH4169 at evaluated temperatures. The single factor milling experiments of GH4169 were carried out at room temperature and evaluated cryogenic levels, and the cutting performance in terms of cutting chips, cutting forces, and tool wear was investigated. The results showed that cryogenic cooling at −130 °C could increase the shear yield strength of the GH4169 by around 19.80% and the length of the cutting chip decreased monotonically by 53.45% compared with the length at room temperature. However, the cutting forces were not monotonically decreased. The cutting forces increased with the decrease of temperature when the initial temperature varied from 20 to −80 °C. However, when the initial temperature further dropped to –130 °C, the cutting forces were reduced by 30.60% for Fx, 24.02% for Fy, and 16.15% for Fz, respectively. Similarly, tool wear at the rake face and flank face is the most severe at –80 °C and the least at –130 °C. The average wear bandwidth at room temperature is 92.06 μm and decreases to 83.358 μm at –130 °C, which is reduced by 9.45%. [ABSTRACT FROM AUTHOR]

In recent years, 3D printing technology has played an essential role in fabricating customized products at a low cost and faster in numerous industrial sectors. Fused deposition modeling (FDM) is one of the most efficient and economical 3D printing techniques. Various materials have been developed and studied, and their properties, such as mechanical, thermal, and electrical, have been reported. Numerous attempts to improve FDM products' properties for applications in various sectors have also been reported. Still, their applications are limited due to the materials' availability and properties compared to traditional fabrication methods. In 3D printing, the process parameters are crucial factors for improving the product's properties and reducing the machining time and cost. Researchers have recently investigated many approaches for expanding the range of materials and optimizing the FDM process parameters to extend the FDM process's possibility into various industrial sectors. This paper reviews and explains various techniques used in 3D printing and the various polymers and polymer composites used in the FDM process. The list of mechanical investigations carried out for different materials, process parameters, properties, and the FDM process's potential application was discussed. This review is expected to indicate the materials and their optimized parameters to achieve enhanced properties and applications. Also, the article is highly anticipated to provide the research gaps to sustenance future research in the area of FDM technologies. [ABSTRACT FROM AUTHOR]

Clinching technology can join thin sheets of various materials, including aluminum alloy, magnesium alloy, steel, titanium alloy, and polymers. Nowadays, with the popularization of the lightweight concept and the application of various sheet materials in manufacturing, clinching technology has highlighted the advantages of being able to adapt to the joining of different sheet materials. With its unique advantages, clinching technology gains wide development space in the field of metal sheet connection. The application of clinching technology in various sheet materials is summarized and analyzed. The clinching process of special materials is also discussed. In addition, some unaddressed issues in the clinching process of special materials are identified in this paper. [ABSTRACT FROM AUTHOR]

A synergistic combination of mechanical properties and corrosion resistance property is desired for most ocean engineering structural applications. In this paper, we prepared a high-entropy alloy (HEA) cladded layer of composition CrFeCoNiNb (atomic %). We aim to attain a balance between the mechanical property and the corrosion resistance property by adjusting the energy density. The prepared CrFeCoNiNb cladded layer with an energy density of 116.7 J/mm2 exhibited excellent mechanical properties and high corrosion resistance. The improved mechanical properties are attributed to fine grain strengthening, solid solution strengthening, and dispersion strengthening. Whereas, the excellent corrosion resistance is due to the formation of Laves corrosion-resistant phase structure and the compact passivation film. The variation of the mechanical properties and corrosion resistance with different energy densities are attributed to the phase composition. The proportion of the Laves phase decreases first and then increases with the increase of energy density, which is the main reason that the microhardness of the cladded layer follows a similar trend. The outcome of our research suggests that the prepared CrFeCoNiNb cladded layer could be explored to realize surface strengthening of load-bearing parts in marine engineering equipment. [ABSTRACT FROM AUTHOR]

The hydro-assisted tube pressing (HATP) process is a new severe plastic deformation method that is proposed in this paper to improve the mechanical properties of long tubes. The pressured fluid between the tube and die eliminates the friction force between the tube and die and, thereby, decreases the required forming force. This facilitates the production of high-strength relatively long tubes. In the current study, this process was applied to a commercial pure copper tube during six passes at room temperature. Then, the hardness, tensile and electrical properties, and also microstructure of the samples were investigated. With increasing the number of passes, the grain size of the copper tube decreased. After two passes of the HATP process, the values of yield strength and ultimate tensile strength increased from 150 and 223 MPa to 347 and 366 MPa, respectively, and the total elongation decreased from 32 to 10%. After four passes, the tube hardness significantly increased from 81 to 132 HV, and a homogeneous distribution of hardness was obtained along with the tube thickness. The electrical conductivity of the copper tube decreased by 3% after two passes. Also, the effective plastic strain and the required processing force were investigated using the Abaqus commercial finite element software. It is concluded that the required force and the strain distribution are independent of the tube length. The hydro-assisted tube pressing method potentially can be used in the industrial production of long tubes with high mechanical strength and electrical conductivity. [ABSTRACT FROM AUTHOR]

Laser-arc welding is increasingly applied for joining aluminum alloys. A critical issue in laser-arc welding Al alloys is the existence of pores which can significantly influence the in-service properties of the welded joints. How to control the porosity, therefore, is of importance in both academic and industrial worlds. In this paper, effects of welding parameters on the degree of porosity in welded joints were investigated. The distribution and size of pores were characterized by X-ray and synchrotron radiation X-ray detection methodology. It was found that the porosity was successfully controlled by adjusting welding parameters. Specifically, the macropores were reduced dramatically by increasing arc currents and decreasing laser powers. Macropore-free joints were obtained with some welding parameters. The mechanism of controlling macropores was presented. Moreover, the results from mechanical testing showed that the pores did not obviously influence the mechanical properties for low percentage of porosity in the range of near 0 to 4%, but decreased the fatigue strength of the joints. EBSD results illustrated that the grain size of the fusion zone was about 74 ± 58 μm, and no obvious texture was found within the fusion zone. [ABSTRACT FROM AUTHOR]

The present paper aims to compare study the effect of porosity and degree of crystallinity on both quasi-static and fatigue behaviours of PA6 and PA12 specimens obtained by the fused filament fabrication (FFF). The glass transition and melting temperatures were measured complementary to understand better the process. Fatigue analysis is here described in visco-elastic domain of material. The results highlight that the mechanical and fatigue properties of PA 12 are better than those of PA6, in spite of almost amorphous state of PA12. Besides, porosity did not reveal the expected influence on these properties. The obtained results are also compared with conventional techniques given by the literature review. [ABSTRACT FROM AUTHOR]

Fused filament fabrication (FFF) has become one of the most popular, practical, and low-cost additive manufacturing techniques for fabricating geometrically complex thermoplastic polyurethane (TPU) elastomer. However, there are still some uncertainties concerning the relationship between several operating parameters applied in this technique and the mechanical properties of the processed material. In this research, the influences of extruder temperature and raster orientation on the mechanical properties of the FFF-processed TPU elastomer were studied. A series of uniaxial tensile tests was carried out to determine tensile strength, strain, and elastic modulus of TPU elastomer that had been printed with various extruder temperatures, i.e., 190–230 °C, and raster angles, i.e., 0–90°. Thermal and chemical characterizations were also conducted to support the analysis in this research. The results showed the ductile and elastic characteristics of the FFF-processed TPU, with specific tensile strength and strain that could reach up to 39 MPa and 600%, respectively. The failure mechanisms operating on the FFF-processed TPU and the result of stress analysis by using the developed Mohr's circle are also discussed in this paper. In conclusion, the extrusion temperature of 200 °C and raster angle of 0° could be preferred to be applied in the FFF process to achieve high strength and ductile TPU elastomer. [ABSTRACT FROM AUTHOR]

This paper investigates the dissimilar friction stir lap welding of AA2198 and AA7075 sheets. The influence of processing parameters, namely welding speed and tool rotational speed on joint features, microstructure, and mechanical properties were studied by implementing a full factorial design of experiments. Axial and transversal forces were continuously measured during the welding process using a sensed fixture aiming at the correlation of processing parameters, forces, and quality of the achieved joints. Obtained outcomes showed hook formation for all the combination of parameters and the existence of a very narrow processing window in which it is possible to avoid the formation of internal defects, such as grooves and tunnels. The influence of the weld bead morphology on the lap shear strength was elucidated proving that the strength is ruled by the hook morphology. The microstructure of the joints was studied and discussed considering also the microhardness distribution. [ABSTRACT FROM AUTHOR]

The paper presents the results of research on the microstructure and selected mechanical properties of the SnSbCu-bearing alloy after friction stir processing (FSP). The Whorl tool was used for modification; the process was carried out using two rotational speeds of the tool: 280 and 450 RPM and a constant linear speed of 355 mm/min. Microstructure studies were performed employing the techniques of light microscopy and scanning electron microscopy along with analysis of the chemical composition of micro-areas. Additionally, the phase composition was investigated by means of the X-ray diffraction method and statistical analysis of the precipitates present in the investigated alloy. In addition, hardness, flexural strength, and uniaxial compression tests were performed before and after FSP modification. It was proved that using FSP to modify the SnSbCu alloy promotes refinement and homogenization of the microstructure, as well as improvement of the flexural strength, whereas no changes in the hardness level were found. [ABSTRACT FROM AUTHOR]

Previous studies have reported the synthesis and mechanical properties of natural hydroxyapatite (HA), but optimization of the measured hardness and compressive strength has not been examined. This paper presents optimization of HAp mechanical characteristics (hardness and compressive strength), using Taguchi grey relational analysis design. In the design, three factors with mixed levels (2 and 3) were employed with the consideration of sintering parameters (0 and 500 Pa compaction pressure, and 900, 1000, and 1100°C sintering temperature), reported in the previous study. The orthogonal array L18 having 18 rows corresponding to the number of tests and the required columns was selected. Results obtained show that HA with better hardness and compressive strength is feasible with little or no compaction pressure. An optimum grey relational grade (GRG) of the synthesized HA is 0.7171 and has an experimental value within 95% confidence interval. The optimum sintering parameters are gotten to be 500 Pa compaction pressure and 1100°C sintering temperature. The result shows that sintering temperature having 99.90 percentage of contribution is the most significant factor, while compaction pressure and residual error are insignificant on the overall hardness and compressive strength of the synthesized HA. [ABSTRACT FROM AUTHOR]

Photopolymerization is an advanced technology to trigger free radical polymerization in a liquid monomer solution through light-induced curing, during which mechanical properties of the material are significantly transformed. Widely used in additive manufacturing, parts fabricated with this technique display precisions up to the nanoscale; however, the performance of final components is not only affected by the raw material but also by the specific setup employed during the printing process. In this paper, we develop a multiphysics model to predict the mechanical properties of the photo-cured components, by taking into account the process parameters involved in the considered additive manufacturing technology. In the approach proposed, the main chemical, physical, and mechanical aspects of photopolymerization are modelled and implemented in a finite element framework. Specifically, the kinetics of light diffusion from a moving source and chain formation in the liquid monomer is coupled to a statistical approach to describe the mechanical properties as a function of the degree of cure. Several parametric examples are provided, in order to quantify the effects of the printing settings on the spatial distribution of the final properties in the component. The proposed approach provides a tool to predict the mechanical features of additively manufactured parts, which designers can adopt to optimize the desired characteristics of the products. [ABSTRACT FROM AUTHOR]

Cold spraying is an innovative coating technology mainly based on the high-speed impact of metallic particles on different substrates. Through the employment of low-temperature gases (air, He, N), spray particles (usually 1-50 μm in diameter) are accelerated to a high velocity (typically 300-1200 m/s) that is generated through a convergent-divergent de-Laval-type nozzle. Severe plastic deformation of particles impacting on the substrate occurs at temperature well below the melting point leading to the unique mechanical properties experienced by such kinds of coatings. In the present paper, the main processing parameters affecting the fatigue behavior of metal-metal cold spray deposits are described. In the present paper, the effect of processing parameters on fatigue properties were analyzed for different materials such as AA7075 sprayed on AA7075 substrate, AA2024 sprayed on AA7075 substrate, and AA2024 sprayed on AZ91 magnesium alloy substrate. Many experimental conditions have been analyzed in terms of particle dimensions and composition, substrate temperature and composition, gas temperature and pressure, and nozzle properties. In particular, they were analyzed those conditions leading to an increase in fatigue life. [ABSTRACT FROM AUTHOR]