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Highlights: [•] The 98.5% relative density W–5wt% Cr alloy was fabricated by SPS method. [•] The Vickers hardness of the annealed samples can reach 760Hv. [•] Obtained nano-scaled microstructure may be beneficial for irradiation resistance of W-based alloy. [Copyright &y& Elsevier]

Abstract: The use of dual phase (DP) steels in the automobile industry unavoidably involves welding and dynamic loading. The aim of this investigation was to evaluate the microstructural change and mechanical properties of laser welded dissimilar DP600/DP980 steel joints. The dissimilar joints showed a significant microstructural change from nearly full martensite in the fusion zone (FZ) to the unchanged ferrite–martensite dual-phase microstructure in the base metal. The welding resulted in a significant hardness increase in the FZ but the formation of a soft zone in the heat-affected zone (HAZ). The dissimilar welded joints were observed to exhibit a distinctive unsymmetrical hardness profile, yield-point-like phenomenon, and single-stage work hardening characteristic, with yield strength and work hardening rate lying in-between those of DP600 and DP980 base metals, and ultimate tensile strength equivalent to that of DP600 base metal. Although the welded joints showed a lower fatigue limit than the base metals, the fatigue life of the welded joints at higher stress amplitudes was almost the same as that of the DP600 base metal. The welded joints failed in the soft zone at the DP600 side under tensile loading and fatigue loading at the higher stress amplitudes. Fatigue crack initiation occurred from the specimen surface and crack propagation was characterized by typical fatigue striation together with secondary cracks. [ABSTRACT FROM AUTHOR]

Abstract: We use phase-field models to characterize the microstructure present in magnesium AZ31 alloy solidified under welding conditions. We focus our attention on the study of the conditions under which a columnar-to-equiaxed transition (CET) is observed in resistance spot welds. Our simulations show how the size and shape of the columnar and equiaxed regions depend on factors such as cooling rate, temperature gradient and the nature of inoculant particles. Our results are compared with experimental observations. In addition, we contrast our findings with predictions from a previously developed steady-state model for the CET. [Copyright &y& Elsevier]