Enhancement of the resistance to hydrogen embrittlement by tailoring grain boundary characteristics in a low carbon high strength steel
Xiaohui Xi, Zhikun Liu, Zhenbo Qin, Tong Wu, Jin‐Liang Wang, Ning Xu, Liqing Chen
Abstract
In this work, the feasibility of using “grain boundary engineering” to reduce the susceptibility to hydrogen embrittlement in a low carbon low alloy steel was examined. By adding Cu element, the fraction of random grain boundary (RGB) exhibited the highest value in the steel with 1%Cu, while the fraction of special grain boundary (SGB) showed a monotonical decline. The slow strain rate tensile (SSRT) test revealed that the elongation loss presented an increase with Cu addition increasing from 1 % to 3 %. This can be explained in terms of hydrogen diffusion, hydrogen trap and crack propagation. The steel with 1%Cu had a higher fraction of high angle grain boundary (HAGB), which contributed to a higher density of hydrogen traps and a lower hydrogen diffusion rate. Moreover, the steel with 1%Cu had the highest fraction of SGB (∑3, ∑5, ∑7 and ∑≥9), which was beneficial to the resistance to crack propagation. Under the combined effect of RGB and SGB, a higher resistance to hydrogen embrittlement was achieved in the steel with 1%Cu.