In the present work, dissimilar butt joints between a low-Ni, medium-Mn austenitic stainless steel, M-Mn SS, and a Ni-Cr austenitic stainless steel, Ni-Cr SS, were processed by utilizing the gas tungsten arc welding (GTAW) technique at different heat inputs. A filler metal of ER308 was employed in the welding process. The filler yields 480 MPa, which is equivalent to the yield strength of M-Mn SS. The microstructural analysis and mechanical performance (i.e., tensile strength and hardness properties) of the concerned joints were studied by using an optical microscope and uniaxial tensile tests, respectively. The results revealed that a duplex structure from austenite matrix and delta ferrite is promoted in the fusion zone (FZ) of the dissimilar joints processed with low and high energy inputs (0.486 kJ/mm and 0.558 kJ/mm). The FZ of the specimens welded at high heat input exhibited the lowest hardness value (151.2 HV) in comparison to heat affected zone (HAZ) (166.3 HV). Moreover, the joints exhibited a low tensile strength of 610 MPa. The achieved strength is significantly lower than the strengths of the base metals (BMs) M-Mn SS and Ni-Cr SS. This is mainly attributed to the inhomogeneous dendritic structure of the FZ with Cr-carbides precipitation.

The cooling slope (CS) casting is the simplest and cheapest technique for producing feedstock materials with non-dendritic microstructure. Such materials are required for semi-solid metal (SSM) processing methods such as thixoforming. In the present investigation, the effect of the pouring temperature and the water cooling on the thixotropic microstructure of commercial A319 Al-Si cast alloy was studied. The results showed that increasing the pouring temperature slightly reduces the bulk porosity of the CS ingots. The ingots poured with water-cooling exhibited slightly lower porosity content than those poured with without water-cooling. Generally, the primary α-Al grains exhibited higher shape factor near the edge of ingot than the middle and center. Ingots poured with water-cooling exhibited lower grain size and shape factor than those poured without water-cooling. Increasing the pouring temperature increases the size α-Al grains.