The effect of deformation on the change of hydrogen diffusion in C-Mn-Si-P Trip 800 steel

Hydrogen diffusion characteristics were studied in C - Mn - Si - P TRIP 800 steel. The steel was tested in as-received state and in states after 5 and 10 % tensile deformation. The steel microstructure consisted predominantly of ferrite, bainite and retained austenite. The tensile deformation resulted in a decrease of the retained austenite content. Hydrogen diffusion characteristics were studied by means of electrochemical permeation method for two current densities in build-up transients. Hydrogen diffusion coefficients of the studied TRIP steel varied from 1,6・10^-7cm²・s^-1 for the as-received state to 1,3・10^-6 cm2・s^-1 for the state after 5 % tensile deformation. The hydrogen diffusion coefficients increased markedly during the second build-up transient reflecting thus the fact that hydrogen trapping was less pronounced