Effect of high-energy shot peening on diffusion behavior of nickel in iron

High-energy shot peening(HESP) was used to make surface self nano-crystallization(SSNC) on pure iron.The thickness of the deformation layer,surface grain size and hardness were characterized by optical microscope(OM),scanning electron microscopy(SEM) and X-ray diffraction analysis(XRD),and then Ni film was penetrated into the surface of iron by the Gleeble 1500 thermal simulation test machine.The SEM was used to compare the diffusion effects.The results showed that the surface of industrial pure iron was refined obviously after the shot peening treatment,its hardness increased significantly and was one time higher than that of the matrix.Under the same conditions,the diffusion rate of Ni in the specimen after SSNC was higher than that without SSNC,so the SSNC technology can improve diffusion effect of Ni on the surface of industry pure iron.