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The study aims to provide firsthand knowledge on finite element simulation (FES) of double-side laser welded (LW) stainless steel 304 (SS-304) thick plates used for automobile application. Double-side welding technique is an idea of achieving complete penetration with minimal heat input. The microstructural evaluation revealed the presence of dendritic growth that results in the enhancement of tensile strength (TS) for the welded sample. There is a slight increase in the delta ferrite content in weldment. The change in microstructure is due to thermal history during solidification. The TS of base metal (BM) was $542\pm 5.1$MPa whereas the welded sample exhibited strength of $554\pm 2.3$MPa. FES was successfully employed to simulate TS with error percentage less than 1.

The fracture behavior of a Zr-based bulk amorphous metal under impact loading using subsize V-shaped Charpy specimens was investigated. Influences of loading rate on the fracture behavior of amorphous Zr-Al-Ni-Cu alloy were examined. As a result, the maximum load and absorbed fracture energy under impact loading were lower than those under quasi-static loading. A large part of the absorbed fracture energy in the Zr-based BMG was consumed in the process for crack initiation and not for crack propagation. In addition, fractographic characteristics of BMGs, especially the initiation and development of shear bands at the notch tip were investigated. Fractured surfaces under impact loading are smoother than those under quasi-static loading. The absorbed fracture energy appeared differently depending on the appearance of the shear bands developed. It can be found that the fracture energy and fracture toughness of Zr-based BMG are closely related with the extent of shear bands developed during fracture.

In this study, the effect of powder particle contents on the mechanical properties of aluminum-based hybrid composites produced by warm accumulative roll bonding (WARB) process was investigated. Three hybrid composite groups with fully annealed AA1060 strips, 1wt.% of MnO₂ and 0, 7.5 and 15wt.% of TiO₂ were first roll-bonded and then the ARB process continued up to eight rolling cycles. In the WARB process, the samples were preheated at 300^∘C for 5min before each rolling cycle. It was realized that increasing the number of ARB cycles with 0 and 7.5wt.% of TiO₂ particles improved the uniformity of TiO₂ particles distribution in the aluminum matrix. Also, in samples with high contents of TiO₂ particles (15%), TiO₂ clusters converted into small clusters with a better distribution through the aluminum matrix. Also, by increasing the number of cycles and TiO₂ wt.% up to 15%, the tensile strength, elongation, tensile toughness and average Vickers microhardness of hybrid composites were increased first and decreased then. Moreover, the effects of ARB cycles and TiO₂wt.% on the fracture surface of hybrid composites have been studied by scanning electron microscopy (SEM). It was found that all the samples fabricated with one and two ARB cycles exhibited a typical ductile fracture containing deep dimples, whereas by increasing the TiO₂wt.% and ARB cycles, a combination of ductile and shear ductile fracture have been detected in the fracture behavior.

In this investigation, Al1060 and pure copper are used to fabricate bi-metal Al–Cu composites via accumulative press bonding (APB) process. The Al and Cu bars were press bonded and continued up to five pressing steps. In the APB technique, the composites manufactured were heated at 320^∘C for about 8min and prior to each forming step. Mechanical properties of these bi-metal composites were assessed in evaluation to Al–Al and Cu–Cu APB processes Metal Matrix Composites (MMCs). It was shown that both Al and Cu deform in the same style in the Al–Cu samples after two steps-APB steps and afterward Cu layers started to neck. Also, it was realized that the average value for the strength of the Al/Cu composites is upper than that of these two MMCs fabricated via one metal. The peeling strength of these products enhanced via the APB steps. Moreover, the effect of APB steps on the fracture and peeling surfaces of bi-metal composites have been investigated by using scanning electron microscopy (SEM).

In aerospace industry, there is a need for aluminum/titanium joints in wing spars of aircraft structures. This research explores the feasibility of joining Ti6Al4V to AA6061 by means of friction welding. Influence of geometrical design on the microstructure and impact strength of dissimilar AA6061/Ti6Al4V joints is investigated. Investigation by scanning electron microscopy reveals deformation of the grains at titanium side along the direction of stress, therefore leading to the formation of TMT (thermo-mechanically treated) zone. The intermetallic compound at the joint interface is attributed to the presence of brittle TiAl and Ti₃Al phases. Rotational speed has a significant influence on the impact strength. The impact energy at the interface was found to be 10.2J when the speed of rotation was set as 1000rpm. Geometry featuring “spearhead with blunt end” is found to give good joint strength with minimum material loss. Fractography studies reveal the presence of few dimples in the welded zone and brittle mode of fracture.

The toughness of blends composed of nylon 6 and acrylonitrile-butadiene-styrene (ABS) compatibilized by using styrene-maleic anhydride (SMA) as a compatibilizer was measured over a wide temperature region. Results reveal that the combining effects of particle size and volume fraction of ABS on the toughness of nylon 6/ABS/SMA blends can be described through plotting brittle-ductile transition of the impact strength versus the interparticle distance (ID) on the assumption that ABS domains relieve the triaxial tension via internal cavitation or interfacial debonding. Moreover, the effect of interfacial adhesion on fracture behavior of nylon 6/ABS/SMA blends strongly depends upon the testing temperature. The difference of relation amomg temperature, fracture behavior and interfacial adhesion can be understood in terms of the deformation mechanisms, i.e. in the case of poor interfacial adhesion, the toughness lies on whether debonding existing at the interface relieves triaxial tension or not. It is believed that for good interfacial adhesion, internal cavitation followed by matrix shear yielding is a predominant factor for toughening. Furthermore, the fracture surface of these blends was probed to elucidate how interfacial adhesion affected the impact strength of the blends.

The effects of cyclic loading conditions (either thermal or mechanical) on the reliability of electronic assemblies are strongly dependent on the performance of solder joints. Most solder joint fatigue models, and the supporting experimental data, do not treat the crack propagation processes that lead to failure. The benefits from a physically based description of crack propagation in solder joints include an accurate representation of the damage produced by cyclic loading and, therefore, a superior basis to evaluate attachment designs and materials. The development of crack growth rate models has been hampered by the lack of experimental capabilities to observe and characterize crack propagation in solder joints and a computational capability to describe the propagation of cracks in solder joints. This paper describes several approaches that have been used to measure crack propagation rates in solders and a new approach to quantify the crack growth rate and its driving force in solder joints by a quantitative analysis of the fracture surface topography.