The Effects of Hydrogen on Toughness of Ultra High Strength Low Alloy TRIP-aided Steels

Abstract

The effects of hydrogen on toughness in three types of ultra high strength low alloy TRIP-aided steels with different matrix structure were investigated. A large amount of hydrogen was charged in these TRIP-aided steels, especially in the TRIP-aided steels with bainitic ferrite matrix austempered in 375 ℃. This was principally associated with high hydrogen solubility in retained austenite and hydrogen trap on dislocations with high density. Excellent impact properties were completed in the TRIP-aided steels with annealed martensite matrix even after hydrogen charging up to 10 ppm. This was caused by uniform fine structure and stable retained austenite which suppressed the crack initiation due to lowering local stress concentration.