Embrittlement damage of low alloy Mn-V steel

This work describes the hydrogen embrittlement damage of tubing made from a commercial low alloy manganese steel containing vanadium. Hydrogen charging of steels was carried out in 0.5 M H2SO4 solution which contained 10 mg/l As2O3 for 2 h under static load. Fractography was carried out using a scanning electron microscope (SEM) equipped with energy dispersive X-ray spectrometry (EDXS). Normalizing the tubing increased the yield strength. Tubing normalized at 900 degreesC is more resistant to hydrogen embrittlement (HE) compared to that in the as-received condition. The improved behaviour of steels when normalized at 900 degreesC can be attributed to a fine ferrite-pearlite microstructure (mean area of pearlite colonies 2.5 times smaller than in the as-received condition) and a beneficial variation in hydrogen trapping behaviour. Initiation of fracture occurred at complex inclusion/matrix interfaces. The size of the inclusions that caused fracture was 2 to 5 mum. (C) 2002 Elsevier Science Ltd. All rights reserved.