N80钢在地层水中的应力腐蚀行为研究

Stress corrosion performance of N80 steel in formation water

分别在空气和地层水两种环境中进行了不同应变速率下N80钢的慢应变拉伸（SSRT）实验,并进行了断口电镜扫描分析。研究发现,N80钢在空气中断口为均匀的韧窝,呈韧性断裂；而在地层水中,出现了晶间断裂,显示出应力腐蚀断裂（SCC）的敏感性,力学性能明显降低,并受到应变速率与温度的共同影响。试片腐蚀率实验结果表明,在应力作用下的N80钢腐蚀速率比无应力状态下高12%,而添加适当的缓蚀剂可以减缓N80钢的应力腐蚀,缓蚀率为38%～43.2%,同时力学性能有所改善。

The stress corrosion performance of N80 steel was experimented respectively under the condition of slow strain rate tension in air and formation water. The corroded fractures on the steel were analyzed with SEM. The fractures on columned samples of N80 steel showed lots of homogeneous dimples in air and was characterized by tough fractures. Many intercrystalline fractures appeared on the steel samples in formation water, which indicates the stress corrosion cracking sensitivity. The fracture shrinkage rates are not proportional to the extending rate, and the mechanical property of N80 steel is worse and influenced by strain rate and temperature. Under the action of stress, the corrosion rate of N80 steel samples increased 12 percent than that without stress. When some proper corrosion inhibitors are put into water, the stress corrosion decreasing rates was 38% to 43%, and the mechanical property can be improved.