微合金化设计耐高温、高H_(2)S分压的HP-13Cr-Cu不锈钢

Micro-alloying design of HP-13Cr-Cu stainless steel with high temperature and high H_(2)S partial pressure resistance

为了提高不锈钢在高温、高H_(2)S分压油气开采环境下的耐蚀性能,通过“溶解-电离-沉积”热-动力学一体化模型明确了微/低合金元素对不锈钢耐蚀性能的影响规律,实现了对不锈钢耐蚀性能的初步调控。通过添加质量分数为1%的铜元素对HP-13Cr不锈钢的抗H_(2)S腐蚀性能进行调控,制备了HP-13Cr-Cu不锈钢。模型计算结果表明,HP-13Cr-Cu不锈钢在H_(2)S腐蚀过程中,铜元素先在不锈钢表面富集,随后进行溶解产生较高摩尔浓度的Cu^(2+),CuS因其溶度积常数较小,所以在腐蚀产物沉积过程中优先沉积,且作为Cr_(2)O_(3)的异质形核位点促进Cr_(2)O_(3)形核,Cr_(2)O_(3)又作为二级异质形核位点进一步提高其他腐蚀产物的形核率,从而使HP-13Cr-Cu在H_(2)S环境下形成的腐蚀产物致密度更高、保护能力更强。H_(2)S腐蚀试验结果表明,与HP-13Cr相比,HP-13Cr-Cu在温度为25~200℃、H_(2)S压力为0.1~0.5 MPa环境下具有更低的腐蚀速率,并且随着温度升高,腐蚀速率下降更加明显。应力加载条件下,HP-13Cr不锈钢发生严重的硫致应力腐蚀开裂,而HP-13Cr-Cu不锈钢在H_(2)S压力为0.1 MPa环境下完全不发生硫致应力腐蚀开裂,在H_(2)S压力为0.5 MPa环境下依然保持良好的抗硫致应力腐蚀开裂性能。腐蚀产物元素分布结果表明,铜元素在金属基体和腐蚀产物中均有富集,腐蚀产物中铬元素含量提高,试验测试结果验证了理论计算的正确性。

The effect of micro/low alloying elements on the corrosion resistance of stainless steel was determined by the integrated model of"dissolution-ionization-deposition".The H_(2)S corrosion resistance of HP-13Cr stainless steel was controlled by adding 1%wt Cu element,and prepared HP-13Cr-Cu stainless steel.The model calculation results show that Cu element first enrich at the surface of stainless steel during H_(2)S corrosion process.Subsequently,high concentration Cu^(2+)is generated by the dissolution of stainless steel,and CuS is the most preferentially deposited during the deposition of corrosion products due to the lower Ksp.Then CuS deposited preferentially promotes Cr_(2)O_(3)nucleation as a heterogeneous nucleation site,and Cr_(2)O_(3)serves as a secondary nucleation site to further improve the nucleation rate of other corrosion products.Thus,the corrosion products formed by HP-13Cr-Cu in H_(2)S environment have higher density and stronger protection.H_(2)S corrosion experiment results indicate that,compared with HP-13Cr,HP-13Cr-Cu has a lower corrosion rate at 25-200℃and 0.1-0.5 MPa H_(2)S.The decrease of corrosion rate of HP-13Cr-Cu is more obvious with the increasing temperature.Serious sulfur induced stress corrosion cracking occurs for HP-13Cr stainless steel under stress.No stress corrosion cracking occurs in 0.1 MPa H_(2)S environment,and good stress corrosion cracking resistance is still maintained in 0.5 MPa H_(2)S environment.The results of element distribution indicate that Cu element is enriched in the corrosion scale and substrate,and concentration of Cr element increase in the corrosion product.The experimental results verify the correctness of the theoretical calculation.