Hydrogen-attacked crack healing with recovering heat treatment of dissected-specimen in vacuum environment

The healing mechanism of hydrogen-attacked crack and its influencing factors to the low carbon steel and Cr - Mo steel during the healing process was studied by recovering heat treatment of split specimens in vacuum. The result showed that crack pacing turned much smaller under the condition of pure heating, especially for crack tips. The healing effect was well related to the length of cracks with the shorter in priority. By the primary mechanism of thermal diffusion, iron and carbon atoms must diffuse at the high speed in steel to realize that plasticity deformation energy (E_s) exceeds and overcomes surface tensile force energy. In addition, phase transformation and stress-strain relationship also have positive effects on the process.