A Review of Research Status of Hydrogen Embrittlement for Automotive Advanced High-Strength Steels

This paper overviewed the current research status and important results of the hydrogen embrittlement (HE) of the representative steel types from 1st to 3rd generation advanced high-strength steel (AHSS): transformation induced plasticity (TRIP) steel, twinning-induced plasticity (TWIP) steel, quenching & partitioning (QP) steel and medium manganese steel. The main conclusions are as follows: the HE sensitivity of TRIP steel is mainly reflected in the reduction of plasticity and the small loss of strength. The HE sensitivity of TWIP steel depends heavily on the strain rate, i.e., the HE susceptibility is significantly increased as the strain rate decreases. Deformation twin boundaries and epsilon/gamma phase interfaces are generally prone to hydrogen-induced cracking, while Sigma 3 annealing twin boundaries are not. However, the epsilon/gamma phase interfaces with Nishiyama-Wassermann orientation relationship, which is similar to the Sigma 3 twin boundaries, could hinder the propagation of hydrogen-induced cracks. HE sensitivity of QP steel is similar to that of TRIP steel. For medium manganese steel containing a large volume fraction of austenite phase, which result in a strong TRIP effect during deformation, the HE susceptibility represented by plasticity loss and strength loss is very high. For TRIP steel, QP steel and medium manganese steel with austenite structure, the main strategy to improve their hydrogen embrittlement is to control the morphology and distribution of austenite structure; for TVVIP Steel, the measures to improve hydrogen embrittlement can be taken by controlling the prestrain rate and Al Alloying.