材料期刊网

目的：针对IS15156标准中对超级13Cr-110马氏体不锈钢使用条件的限制，及不同研究者对其开裂条件的不同观点，研究超级13Cr-110马氏体不锈钢在不同温度、不同低H2S分压条件下的开裂敏感性。方法通过模拟我国西部酸性油田低H2S高CO2环境，利用高温高压设备，进行了三点弯曲试验，并结合失重法测试腐蚀速率。结果在硫化氢分压为6 kPa时，超级13Cr-110马氏体不锈钢腐蚀速率随温度降低而减小，80℃时仅0.0031 mm/a，但应力腐蚀开裂敏感性增加。在210℃条件下，当硫化氢分压从6 kPa升至165 kPa时，腐蚀速率变化不明显。同时，超级13Cr-110马氏体不锈钢的开裂敏感性降低，但长周期实验依然会发现裂纹。结论通过对裂纹及断口形貌分析发现，超级13Cr-110马氏体不锈钢在低H2S分压条件下的开裂类型为氢脆型硫化物应力腐蚀开裂，即局部钝化膜遭受破坏，进而发生点蚀，导致氢在应力集中区域聚集，最后发生氢脆。硫化氢分压从6 kPa增加到165 kPa，局部腐蚀受到抑制，由点蚀导致开裂的敏感性降低。超级13Cr-110马氏体不锈钢不一定能在标准中推荐的硫化氢分压不大于10 kPa的条件下使用。

ABSTRACT:Objective Aimed at the service restrictions of super 13Cr-110 martensite stainless steel in standard IS15156 and the various viewpoints of its cracking condition, cracking sensibility of super 13Cr-110 martensite stainless steel at different temperatures and diverse low H2S partial pressures was studied. Methods The experiments of weight loss and three point bend-ing test were carried out in the simulated corrosion environment based on acid oilfield containing low H2S and high CO2 in West China. High temperature and pressure autoclave was used during the test. ResultsThe corrosion rate of super 13Cr-110 marten-site stainless steel diminished with the decrease of temperature. It was 0.0031 mm/a at 80℃. Nevertheless, the stress corrosion cracking sensibility increased. The corrosion rate changed a little when H2S partial pressure rose from 6 kPa to 165 kPa at 210℃. Meanwhile, the cracking sensibility of super 13Cr-110 martensite stainless steel decreased. But fissures also appeared in long-term test. Conclusion Under low H2S partial pressure, the cracking type of super 13Cr-110 martensite stainless steel showed hydrogen embrittlement sulfide-stress cracking according to the analysis on the pattern of fissure and fracture. Firstly, local passive film was damaged and then pitting corrosion occured which led to the assembling of H. Finally, hydrogen embrit-tlement happened. With the H2S partial pressure lifting from 6 kPa to 165 kPa, the cracking sensibility of 13Cr-110 caused by pitting corrosion reduced due to the restraining of pitting corrosion. Super 13Cr-110 martensite stainless steel might not be ap-plicable in the environment containing no more than 10 kPa H2S as recommended in the standard.