Evaluation of the influence of hydrogen on some commercial DP, Q&P and TWIP advanced high-strength steels during automobile service

The hydrogen influence was evaluated (A) for laboratory conditions with hydrogen concentrations larger than in service, and (B) at substantial loading rates to simulate a crash. Hydrogen in the studied laboratory conditions caused minimal influence for 980DP and 1200DP, and some influence for 980DP-650YS, 980DP-700YS, 980QP and 950TW. Simulated crash situations caused some influence for 980DP, 980QP and 950TW; their properties quickly reverted after the end of hydrogen charging. Two new mechanisms are proposed: (i) hydrogen enhanced macroscopic plasticity (HEMP) decreasing the yield stress, and (ii) hydrogen assisted micro-fracture (HAM) decreasing ductility at fracture at the ultimate tensile strength.