The role of reverted transformation in hydrogen embrittlement of a Cu-containing low carbon high strength steel

Abstract

This work presents an investigation on the role of reverted transformation in hydrogen embrittlement, aiming at revealing the influencing mechanism of austenite and grain boundary characteristics on hydrogen embrittlement (HE) susceptibility during reverted transformation. The results showed that HE susceptibility decreased with the annealing temperature increasing from 680 °C to 720 °C, which attributed to a combined effect of austenite and grain boundary distribution. Both the fractions of austenite and high angle grain boundary (HAGB) increased with the annealing temperature increasing from 680 °C to 700 °C, which resulted in a lower HE susceptibility at 700 °C due to strong H storage of austenite and HAGB. As the annealing temperature further increased to 720 °C, the fraction of austenite exhibited a decline, but the fraction of HAGB monotonously increased. As a result, a lower HE susceptibility was achieved at 720 °C. This indicated that grain boundary distribution played a determining role in the resistance to HE. We ascribed this to the variant selection and Bain/CP grouping.

Keywords

• Low carbon low alloy steel
• Reverted transformation
• Austenite
• Grain boundary characteristics
• Hydrogen embrittlement