The present work discusses about the mechanical and metallurgical properties of Incoloy 800 H friction welded joints. The process parameters namely friction pressure, friction time, upsetting pressure, upset time, and rotational speeds were varied from low level to high level to study their effects on the properties of the weldments. The tensile tests were carried out at four different temperatures namely at room temperature, 550, 650, and 750 °C. From the results, it is observed that as the testing temperature increased, there was a reduction in tensile strength of welds. The friction welds had higher hardness than the base metals. This was due to the formation of secondary phases (γ′ and M23C6) in friction welds. The tensile and impact fracture surfaces were further analyzed through SEM and finally the individual effects of the parameters with respect to the microstructures variation in the welds were studied.

In this present study, the influence of different casting processes on high cycle fatigue behavior of Mg–10Gd–3Y–0.5Zr magnesium alloy was investigated by using porosity-free low-pressure sand-casting (LPS) bars and gravity permanent mold casting (GPM) ingots. The results show that the fatigue properties of both LPS and GPM Mg–10Gd–3Y–0.5Zr alloy in as-cast condition are determined by Mg matrix and eutectic phase. However, the fatigue property improvement for LPS alloy by T6 heat treatment is significantly superior to that of GPM alloy. The different degree of enhancement of fatigue properties for two conditions of the alloy is related to different crack initiation mechanism. The fatigue crack of the LPS alloy initiates from the free surface of the sample, while the crack of the GPM alloy initiates from porosities or inclusions near the surface of the sample. Meanwhile, the crack of slip band has a crucial effect on the fatigue crack initiation of both as-cast and T6 conditions for LPS alloy.

In the present study, Ti–6Al–4V alloy sheets having a thickness of 1.6 mm and 2 mm are chosen for carrying out weldability studies using gas tungsten arc welding (GTAW) process. The quality of the weld was examined through metallographic (macro- and micrographs) analyses. The welded specimens were subjected to mechanical tests to examine the behavior of tailor welded blanks (TWBs). Grain coarsening at fusion zone (FZ) and heat affected zone was confirmed through optical microscope. Transmission electron microscopy images showed the presence of thin α-phases surrounded by β-grains at FZ. The maximum hardness distribution of 383 HV is obtained at FZ. Tensile test results revealed an increase of 3.58% strength as compared to the thin base metal. At fracture surface, the presence of various sized dimples was identified through SEM. Erichsen cupping test showed that formability performance of the TWB was affected by a negligible percentage.