Characterization of Metallurgical and Mechanical Properties of Thixowelded AISI D2 and AISI 304 Steels

In this study, AISI D2 tool steel was thixowelded with AISI 304 austenitic stainless steel by using a direct partial remelting technique. The joining parameters (temperature, soaking time, and contact area) have been investigated by studying their effects on the mechanical and metallurgical properties of the thixowelded joint. The joint interfacial microstructures were investigated by optical microscopy, scanning electron microscopy equipped with an EDX analyzer, and x-ray phase analysis was performed to identify the phase evolution. Mechanical characterization was determined by tensile and micro-hardness tests. Maximum tensile strength that was achieved is 635 MPa at 1300 °C, with a 5 mm insert diameter and 10 min holding time. This represents 80% of the D2 base metal strength. The joints were fractured on the D2 base metal side close to the diffusion zone characterized by brittle fracture. Consequently, the joints also achieve a full penetration weld with a smooth and uniform hardness profile.