Investigating on the macroscopic morphology, microstructure and mechanical properties of Al0.3CoCrFeNi-HEA/304 stainless steel dissimilar welded joints

Abstract

High-entropy alloys (HEAs) are newly developed materials that have many excellent properties, such as a high strength-to-weight ratio and excellent tensile properties. If high-entropy alloys and stainless steel are joined by welding, the advantages of their properties can be balanced. In this paper, dissimilar lap joining of Al_0.3CoCrFeNi-HEA with 304 stainless steel was achieved using gas tungsten arc welding (GTAW) with different heat inputs. Macroscopic morphology, microstructure analysis and mechanical property tests of the welded joints were carried out. The results showed that the macroscopic morphology of the dissimilar welded joints is well-formed under different heat inputs. The penetration and width of the weld seam increased with the heat input, and the lap area of the welded joint also increased. There was the same microstructure in the weld seam with different heat inputs, including columnar dendrites near the fusion line and equiaxed dendrites at the weld centre. The ultimate shear strength of the welded joints increased from 442 MPa to 560 MPa with increasing heat input, and the elongation of the welded joints increased from 26 % to 41 %. With increasing heat input, the average microhardness of the weld zone (WZ) was approximately 145 HV.