Building a gradient structure can achieve overall improvement of multiple properties of metal materials. However, the investigation on hydrogen embrittlement (HE) behavior of gradient structure alloys has not been reported so far. This study investigated HE of pure iron with gradient microstructure induced by pre-torsion. The results reveal that with an increase in pre-torsion angle, the resistance to HE of alloys decreases. Fracture surface observation demonstrates that hydrogen uncharged samples present ductile cup-shape fracture, whereas hydrogen charged samples exhibit brittle spiral patterns, mainly depending on pre-torsion level. Additionally, microscopical hydrogen-assisted cracking mechanism of gradient structured pure iron has been proposed.

构建梯度结构可以实现金属材料多项性能的整体提升。然而，到目前为止，关于梯度结构合金的氢脆（HE）行为的研究尚未见报道。本研究调查了由预扭转引起的具有梯度微观结构的纯铁的 HE。结果表明，随着预扭转角的增加，合金的抗HE性能下降。断口观察表明，不带氢的样品呈现韧性杯状断裂，而带氢的样品则表现出脆性螺旋图案，主要取决于预扭转水平。此外，还提出了梯度结构纯铁的微观氢辅助裂解机制。