Hydrogen Permeation and Hydrogen Embrittlement Behavior of GPa‐Grade Hot‐Rolled Transformation‐Induced Plasticity Steels under Different Coiling Temperatures

The hydrogen permeation and hydrogen embrittlement behavior are studied in GPa‐grade hot‐rolled transformation‐induced plasticity steels with different volume fractions of retained austenite, which is obtained by different coiling temperatures. The hydrogen permeation test indicates that the breakthrough time ( t b ), apparent hydrogen concentration ( C 0R ), and hydrogen trap density ( N T ) increase with increasing coiling temperature, while the effective hydrogen diffusion coefficient ( D eff ) decreases. The results of the slow‐strain rate tensile test show that hydrogen charging can reduce the elongation of the experimental steel but has little impact on the strength of the experimental steel. When the hydrogen charging time is increased to 60 min, the free hydrogen and hydrogen captured by the trapping sites increase significantly, resulting in severe hydrogen embrittlement damage and intergranular fracture. The hydrogen embrittlement resistance of GPa‐grade hot‐rolled TRIP steels can be improved by enhancing the stability of retained austenite to increase the critical strain at which the TRIP effect occurs.