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Studies on Multi-pass Friction Stir Processing (FSP) of Fe49.5Mn30Co10Cr10C0.5, a metastable dual-phase High Entropy Alloy (HEA), were carried out with the aim to systematically investigate the microstructural changes occurring during different passes, and to evaluate the mechanical response of this alloy with progressive passes. A reduction in grain size and a change in HCP volume fraction was observed after each pass. Dynamic recrystallization, occurring during FSP, led to grain refinement, and the transformation induced plasticity (TRIP) effect resulted in observed changes in HCP phase fraction. One-pass FSPed material exhibits a higher work hardening rate and a higher ultimate tensile strength (UTS.) value, as compared to both, an annealed and two-pass FSPed material. This is due to a combination of two factors, a small grain size and a large fraction of metastable Face Centred Cubic (FCC) phase, in the microstructure of the one-pass material.

To make metallic parts for manufacturing industries, additive manufacturing (AM) has acquired considerable significance. However, most efforts have concentrated on powder-based techniques, and there remains a dearth of the experimental evidence on the mechanical characteristics and structural behavior of metallic elements produced using wire-and-arc additive manufacturing (WAAM). This article examined the optimal parameters to enable bulk fabrication of thick walls made with a SS410 wire. The objective was to assess the optimized variables utilizing response surface methodology (RSM), followed by the microstructural analysis and mechanical property evaluation. During optimization, the influence of wire feed speed, travel speed, and gas flow rate on bead width and height was determined. Further, the optimized variables resulted in the successful formation of thick walls. Secondly, the microstructural analysis mainly featured the martensite and delta ferrite, with the latter’s percentage increasing with build height. The maximum micro-hardness of 452 HV was obtained at the base of the wall. In addition, the remarkable increases in the standard deviation of micro-hardness represent the great extent of anisotropy in the thick wall. Moreover, the maximum UTS (803 ± 8 MPa) and YS (659 ± 10 MPa) are achieved for the OB sample, which is similar to conventional components. However, the current investigation’s percentage elongation of 5% (max) demands more study before the actual use of the WAAM manufactured SS410 material. Therefore, due to the significant degree of anisotropy and poor percentage elongation, the findings conclude that post-processing is required after bulk SS410 manufacturing.