X80钢组织状态对CO抑制氢脆作用的影响

The effect of X80 steel microstructure on CO inhibition of hydrogen embrittlement

CO可抑制氢分子在管道内壁的吸附,有效降低输氢管道发生氢脆的风险,是保证在役管道安全输氢的潜在方式,但CO对氢脆指数的影响度与钢材的材料组织状态有关。以X80钢为研究对象,针对母材、预应变母材及两种根焊缝,通过在氮气、氢气、氢气+0.1%CO(分压,下同)3种环境中进行慢应变速率拉伸实验,研究不同状态管体的氢脆指数及CO影响度。结果显示,母材、预应变母材、自动焊缝、手工焊缝在12 MPa纯氢中的氢脆指数分别为35.75%、43.72%、39.28%、33.66%,均具有极高的氢脆失效风险;加入CO可显著降低材料的氢脆敏感性,0.1%CO可使上述4类试样的氢脆指数分别降低至15.66%、17.54%、23.16%、25.33%,其中手工焊缝的降低程度最小,是实验对象中受CO影响程度最小的一类。建议后续针对手工焊缝区域,研究不同氢分压下足以抑制氢脆发生的最低CO加入量。

Carbonic oxide(CO)can effectively reduce the risk of hydrogen embrittlement(HE)of hydrogen pipelines by inhibiting the adsorption of hydrogen molecules on the inner wall,which provides a potential solution to ensure the safe hydrogen transportation by the in-service pipelines.However,the influence of CO on HE index is related to the microstructure of steel materials.A case study was carried out to X80 steel,for which slow strain rate tension tests were conducted on the base material,pre-strained base material and two different types of root weld under the conditions of nitrogen,hydrogen and hydrogen+0.1%CO(by partial pressure,the same below),so as to study the HE index and CO influence degree of pipe body in different states.According to the results,the HE indexes of the base material,pre-strained base material,automatic weld and manual weld under the condition of 12 MPa pure hydrogen are 35.75%,43.72%,39.28%and 33.66%,respectively,showing a very high risk of hydrogen embrittlement.However,the hydrogen embrittlement sensitivity could be reduced greatly with the addition of CO.Specifically,adding 0.1%CO can lower the HE index of the four kinds of specimens to 15.66%,17.54%,23.16%and 25.33%,respectively.Among them,the HE index of manual weld has the minimum reduction,which is least affected by CO among the studying objects.Therefore,it is recommended to study the minimum CO addition that could inhibit the HE at various hydrogen partial pressures for the manual weld area in future.