Effects of Time and Temperature on the Shear Strength of Dissimilar Diffusion Joints of CPTi to Stainless Steel.

Transition joints between commercial pure titanium (CP-Ti) and 304 stainless steel (304-SS) have been produced employing diffusion welding technique in the temperature range of 800-950 ºC, under a uniaxial pressure of 7 MPa in argon atmosphere. The evaluation of the transition joints has been carried out using shear tests. The shear strength was found to be a function of joint surface area and volume fraction of brittle intermetallic phases such as σ, FeTi, Fe2Ti,… which have been characterized using scanning electron microscopy and energy dispersive spectroscopy. Increasing the temperature and time of the diffusion welding process increased joint surface area and accelerated elemental diffusion across the joint interface which resulted in higher shear strength. But as the volume fraction of the brittle intermetallic phases and Kirkendal voids increased at higher temperature and time, the bond shear strength decreased. Optimum shear strength was found to be 168 MPa which related to the joint produced at temperature and time of 900ºC and 30 min, respectively.

کلیدواژه ها:

Diffusion joints ، Titanium ، Shear Strength ، Stainless steel