目的 评价 90SS 和 90SS-3Cr 油管钢在 H2S-CO2 环境下的硫化物应力腐蚀开裂(SSCC)行为,并分析其断裂机理。 方法 利用四点弯曲实验和慢应变速率拉伸实验,结合显微组织分析、扫描电子显微镜分析技术,研究 90SS 和 90SS-3Cr 两种钢材在 H2S-CO2 环境下的应力腐蚀开裂行为和断口形貌特征。结果 90SS-3Cr 钢的显微组织中存在更多的非金属夹杂物。 经过 720 h 四点弯曲实验后,90SS 和 90SS-3Cr 试样表面均未出现宏观及微观裂纹,表现出良好的抗硫化物应力腐蚀开裂能力。 在慢应变速率拉伸实验中,当 H2S 浓度由 0 增加至 6 mol/ L 时,90SS-3Cr 试样的断后伸长率 δ、断面收缩率 φ 及断裂时间 t分别下降了 71. 6% ,69. 6% ,61. 4% ,远高于 90SS 钢的塑性损失(分别下降 2. 9% ,52. 5% ,10. 3% )。 断口形貌分析表明,90SS-3Cr 钢在较低浓度 H2S 时就由塑性断裂向脆性断裂转变。 结论 随着 H2S 浓度的升高,90SS 和 90SS-3Cr 钢的塑性损失增加,抗 SSCC 能力均下降。 相比 90SS 钢,90SS-3Cr 钢对应力腐蚀开裂更为敏感。

Objective To evaluate the sulfide stress corrosion cracking (SSCC) behavior of 90SS and 90SS-3Cr tube steels in H2S/ CO2 environment, and determine the fracture mechanism. Methods The SSCC behavior and fracture morphologies of 90SS and 90SS-3Cr tube steels in H2S/ CO2 environment were investigated by using four point bend test (FPB), slow strain rate test (SSRT), microstructure and scanning electron microscope (SEM) analysis. Results For 90SS-3Cr, more non-metallic inclusions appeared in the microscopic structure. After the FPB test for 720 hours, there were neither macroscopic nor microcosmic cracks on the surfaces of 90SS and 90SS-3Cr specimens, which meant that they possessed a favorable SSCC resistance. However, the SSRT tests indicated that as the concentration of H2S increased from 0 mol/ L to 6 mol/ L, the elongation, the reduction of cross section and the fracture time of 90SS-3Cr steel decreased by 71. 6% , 69. 6% and 61. 4% , which were much higher than that of 2. 9% , 52. 5% and 10. 3% of 90SS steel respectively. The fracture morphology analysis showed that the fracture of 90SS-3Cr steel transformed from ductile fracture into brittle fracture at lower H2S concentrations. Conclusion The SSCC resistance of both 90SS and 90SS-3Cr tube steels decreased with the rising of H2S concentration. 90SS-3Cr specimens were more prone to fracture than 90SS steel.