Effect of hydrogen on the properties and fracture characteristics of TRIP 800 steels

The paper describes effect of hydrogen on the properties and fracture characteristics of two variants of TRIP 800 C–Mn–Si steels. The effect of hydrogen was studied by means of tensile tests on specimens previously charged by hydrogen. Hydrogen provoked embrittlement in both variants but only for very high hydrogen content. Hydrogen embrittlement manifested itself mainly by a loss of plasticity. Both steel variants were able to absorb a large amount of hydrogen, up to 50 ppm. Concerning fractographic characteristics, steels containing higher hydrogen content displayed transgranular cleavage fracture. In exceptional cases, an irreversible embrittlement was revealed initiating on non-metallic inclusions.

► TRIP 800 steels can be embrittled to different levels by hydrogen.
► TRIP 800 steels absorb much more hydrogen in comparison with other advanced high strength steels, up to 50 ppm.
► Retained austenite (7–11%) cannot preserve the steels from hydrogen embrittlement.
► Non-metallic inclusions seem to be the preferential sites for the crack initiation.