Effect of reverted austenite fraction on hydrogen embrittlement of TRIP-aided medium Mn steel (0.1C-5Mn)

The present work was attempted to evaluate the influence of reverted austenite (RA) fraction on hydrogen embrittlement (HE) of a hot rolled transformation-induced plasticity (TRIP)-aided medium Mn steel (0.1C-5Mn) by using electrochemical charging, slow strain rate tensile (SSRT) WA and thermal desorption spectrometry (TDS) analysis. Different volume fractions of RA (similar to 10-30 vol %) in the tested steel sheet were obtained by changing intercritical annealing time. The result of TDS analysis demonstrated that the charged hydrogen is primarily diffusible hydrogen corresponding to low-temperature hydrogen desorption peak and its concentration increases almost linearly with an increase in the volume fraction of RA. It was found that the intercritically annealed specimen exhibits an increasing susceptibility to HE with an increase in the volume fraction of RA primarily due to the increased RA transformation to martensite during tensile deformation. It is thus regarded that the TRIP effect is harmful to the HE resistance of TRIP-aided steels, and therefore both the mechanical stability and amount of RA have a strong influence on the HE behavior of TRIP-aided medium Mn steel.