An integrated experimental and modeling approach to determine hydrogen diffusion and trapping in a high-strength steel

Abstract

The hydrogen diffusion and trapping in AISI 4330 V high-strength steel is investigated by repetitive electrochemical hydrogen permeation tests, thermal desorption analysis, and hot and melt extraction. The analysis is coupled with a numerical model based on McNabb and Foster's kinetics with varying degrees of trap occupancy. The trapping parameters are obtained by fitting the numerical model to the experimental data, which permits to describe the diffusion and trapping processes for all tested conditions. In addition, the predictions calculated by the model are critically discussed and compared with those derived from usual approaches based on analytical solutions from Fick's laws and from Choo and Lee's method. An important difference is observed, indicating that the use of general analytical methods may not be adequate in the case of the studied steel. The use of more rigorous analysis provides a better understanding of trapping phenomenon and improved predictions of charging times and contents.