Influence of diffusion bonding parameters on the structure and properties of titanium and stainless steel joints with copper interlayer

Purpose of this paper is investigating if the effect of diffusion bonding parameters on the microstructure and mechanical properties of the joints. Design/methodology/approach: Titanium and X5CrNi18-10 stainless steel samples were joined by diffusion bonding using copper foil as a filler metal at temperatures of 850, 875, 900, 925, 950 and 1000°C. From the stainless steel site of joint in all samples, regardless of the temperature of the process, there were formed layers of FeTi phase, and additionally layers of Fe2Ti at 925, 950 and 1000°C. Findings: The structure of the joint from the titanium site was composed of the eutectoid mixture αTi+CuTi2 and layers of phases CuTi2, CuTi, and Cu4Ti3. Hardness of joints reached higher value than for titanium and stainless steel, and it achieved value from 185 to 580 HV. The hardest phase was FeTi. The maximum shear strength was achieved for joints performed at 900°C. Researches limitations/implications: The structural examinations have shown significant changes in joints and relatively expansive diffusion zones on the borders of the joined materials. Structures of joints depended on the temperature of the process. Originality/value: The useful properties have led to a considerable interest in joining titanium and titanium alloys to steel (especially stainless steel) for application in aerospace, transportation, petrochemical and power generation industries.