Hydrogen embrittlement properties of nitrogen added ultra-high-strength TRIP-aided martensitic steels evaluated by using conventional strain rate technique

摘要

Hydrogen embrittlement properties of nitrogen-added TRIP-aided martensitic steels for improving the fuel efficiency of vehicles due to the weight reduction and the impact safety were evaluated by using conventional strain rate tensile tests. Decrease in the total elongation due to hydrogen of a 100-ppm-nitrogen-added TRIP-aided martensitic steel was small in comparison with that of the TRIP-aided martensitic steel without nitrogen. This was attributed to refinement of martensite lath matrix. On the other hand, hydrogen charging decreased the total elongation of a 200-ppm-nitrogen-added TRIP-aided martensitic steel, and decrease in the total elongation of the 200-ppm-nitrogen-added TRIP-aided martensitic steel was more than that of the 100-ppm-nitrogen-added TRIP-aided martensitic steel. This might be caused by the promotion of crack initiation at AlN and AlN/matrix interfaces induced by trapped hydrogen.