Microstructure Evolution and Corresponding Shear Strength of Incoloy 825/Carbon Steel Bimetal Prepared by Diffusion Bonding

The present research utilized diffusion bonding to create a metallurgically bonded Incoloy 825/carbon steel bimetal. The interfacial bonding behavior of bimetals was investigated using a variety of heat treatment technologies. The interfacial bonding shear strength increased initially and then decreased with increasing tempering time, reaching a maximum at 45 minutes. The cohesion strength was attributed to the diffusion distance and diffusion gradient of chromium in terms of interfacial diffusion behavior. The precipitation behavior of carbides and their associated cohesion strength were observed as a function of tempering time using an image-based analysis technique. The uniform diameter, area, and sphericity of the carbides resulted in a high cohesion strength. Additionally, a nanoindentation technique was used to characterize the interfacial cohesion behavior, taking into account dislocation multiplication and localized mechanical behavior during deformation. The critical shear strength of dissimilar metals near the bimetal interface reaches its maximum and the geometrically necessary dislocation (GN(D) densities remain constant after 45 minutes of tempering, indicating that a high interfacial bonded shear strength may be attributed to localized compatible deformation of dissimilar metals near the bimetal interface.