Purpose

With excellent mechanic properties and hydrogen embrittlement (HE) resistance, 12Cr2Mo1R(H) steel is suitable to make hot-wall hydrogenation reactors. However, longtime exposure to a harsh environment of high-pressure hydrogen at medium temperature in practical application would still induce severe hydrogen uptake and eventually damage the mechanical properties of the steel. The study aims to evaluate the HE resistance of the steel under different tensile strain rates after hydrogen charging and analyze the hydrogen effect from atomic level.

Design/methodology/approach

This research studied the HE properties of 12Cr2Mo1R(H) steel by slow strain rate tests. Meanwhile, the effect of hydrogen on the structures and the mechanical properties of the simplified models of the steel was also investigated by first-principle calculations.

Findings

Experimental results showed that after hydrogen pre-charging in this work, hydrogen had little effect on the microstructure of the steel. The elongations and reduction of cross-sectional area of the samples reduced a lot, by contrast, the yield and tensile strengths changed slightly. The 12Cr2Mo1R(H) steel was not very susceptible to HE with a maximum embrittlement index of about 20.00%. First principles calculation results showed that after H dissolution, lattice distortion occurred and interstitial H atoms would preferentially occupy the tetrahedral interstitial site in bcc-Fe crystal and increase the stability of the supercells. With the increase of H atoms added into the simplified model, the steel still possessed a good ductility and toughness at a low hydrogen concentration, while the material would become brittle as the concentration of hydrogen continued to increase.

Originality/value

These finds can provide valuable information for subsequent HE studies on this steel.

中文翻译：

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通过慢应变速率试验和第一性原理计算研究12Cr2Mo1R（H）钢的氢脆

目的

12Cr2Mo1R（H）钢具有出色的机械性能和耐氢脆性（HE），适用于制造热壁加氢反应器。然而，在实际应用中，长时间暴露于中等温度的高压氢气的苛刻环境下，仍会引起严重的氢气吸收并最终损害钢的机械性能。

设计/方法/方法

本研究通过慢应变速率试验研究了12Cr2Mo1R（H）钢的HE性能。同时，还通过第一性原理计算研究了氢对钢简化模型的组织和力学性能的影响。

发现

实验结果表明，在进行氢预充后，氢对钢的显微组织影响很小。样品的伸长率和横截面积的减小大大降低，相反，屈服强度和拉伸强度略有变化。12Cr2Mo1R（H）钢对HE的敏感性不高，最大脆化指数约为20.00％。第一性原理计算结果表明，H溶解后，发生晶格畸变，间隙H原子优先占据bcc-Fe晶体中的四面体间隙位置，从而增加了超晶胞的稳定性。随着简化模型中添加的H原子的增加，钢在低氢浓度下仍具有良好的延展性和韧性，

创意/价值

这些发现可以为后续对该钢进行HE研究提供有价值的信息。