Investigation of interface microstructure and properties of copper/304 stainless steel fabricated by explosive welding

Abstract

Explosive welding is a solid state welding process that is used for the metallurgical joining of two or more dissimilar metals. This paper presented a systematic study of microstructure and properties of copper/304 stainless steel fabricated by explosive welding. The microstructure and chemical composition were evaluated using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The properties were performed by the nanoindentation tests and bending experiments of the microcantilevers, and the microcantilevers were milled out using the Focused Ion Beam (FIB) system. The results showed that the interface between this couple metals presents a typical wavy structure. There are some vortex regions in front of the crest, which are strong intermixing of this couple metals. The diffusion layer and melting layer are two typical layers at the interface. The diffusion layers are formed by strongly collision points, while the melting layers only appear on the stainless steel side. The average nanohardnesses of diffusion layer and melting layer are between that of copper and 304 stainless steel. The nanohardness of this couple metals exhibits increasing trend from 0° to 60°, while decreasing trend from 60° to 90°. The nanohardness in Area 4 of the vortex region is highest, where is the highest temperature. The average flexural strength of micro-cantilevers shows the same change rules with the nanohardness.

Keywords

• Explosive welding
• Wavy structure
• Diffusion layer
• Melting layer
• Nanoindentation