Influence of Allotropic Transformation on Diffusion Welding

Study on Diffusion Welding (Report 8)

Abstract

Rods of pure iron and titanium were welded at cycling temperature containing transformation temperature and constant temperatures which were above and below transformation temperature. The effect of allotropic transformation on the process of diffusion welding has been investigated, compared with isothermal welding.
The following results were obtained.
1.Tensile strength of welded joint is due to welding deformation. As welding deformation is markedly accelerated by repeated transformation during welding compared with isothermal welding, application of transformation to diffusion welding makes welding pressure and time deciease.
2.The shrinkage and decrease of voids along welding interface is accelerated a little by repeated transformation during heating under no load, not due to the acceleration of diffusion, but due to surface roughening.
3.Diffusion coefficient is not enhanced by allotropic transformation.