The stress induced hydrogen diffusion behavior and the sensitivity of hydrogen embrittlement at the heat affected zone of weld part based on analytical solution

The analytical solution of hydrogen diffusion and concentration around the heat affected zone of weld part was derived by taking account for the effect of residual stress on hydrogen concentration. Based on the theoretical analysis, the sensitivity of hydrogen embrittlement was formulated and it is proportional to DK ², where D is diffusion coefficient, K is stress gradient term of residual stress approximated by linear function. It was in good agreement with that previously obtained by numerical analysis. This result shows that the law of hydrogen sensitivity is commonly valid independent of boundary condition when the distribution of residual stress is approximately written by linear functions of the distance in the heat affected zone. Furthermore the analysis of the period when hydrogen embrittlement becomes remarkable was conducted. This result enables us to predict the behavior of hydrogen embrittlement at the heat affected zone of weldment.