Diffusion bonding of surface self-nanocrystallized Ti-4Al-2V and 0Cr18Ni9Ti by means of high energy shot peening

By means of high energy shot peening (HESP), surface nanostructured layers were synthesized on the ends of Ti-4Al-2V titanium alloy and OCr18Ni9Ti austenitic stainless steel bars. Using the peened surfaces for mating surface, constant temperature and pressure diffusion bonding (CTPDB) was applied to prepare joints of Ti-4Al-2V/OCr18Ni9Ti in the temperature rang of 800-900 degrees C for 20min under a uniaxial load of 8 MPa in vacuum. Tensile strengths of joints were tested, longitudinal section microstructures of joints were analyzed by using scanning electron microscope (SEM), meanwhile, concentrations of Fe, Ti, Cr and Ni in diffusion layers were measured by using energy dispersive spectroscope (EDS), and the diffusion coefficient and diffusion activation energy of Fe atom in the Ti-4Al-2V side were calculated. Results shows that the maximum tensile strength of 327 MPa is obtained when bonding temperature is 850 degrees C, the diffusion activation energy of Fe atom is far less than that in coarse grain sample, and the diffusion coefficient of Fe atom is higher than that in convention coarse grain sample.