应力应变对316L液控管线热采环境中应力腐蚀行为的影响

Effect of stress-strain on stress corrosion behavior of 316L hydraulic control pipeline in thermal recovery environment

为研究应力应变对热采井安全阀液控管线电化学特征及应力腐蚀行为的影响,利用高温高压釜模拟260℃、1%(体积分数)氧分压热采环境对316L液控管线进行应力腐蚀实验研究,并采用SEM、EDS进行表征。结果表明,应力应变使316L材质液控管线钝化膜产生微裂纹,使得管线的耐蚀性能变差。模拟高温高压含氧热采环境下,氧气促使微裂纹变为小阳极,钝化膜表面为大阴极,裂纹尖端自催化发展,最终导致316L液控管线发生应力腐蚀开裂,出现多条平行的环向裂纹。

In order to study the effect of stress and strain on electrochemical characteristics and stress corrosion behavior of hydraulic control pipeline of safety valve in thermal recovery well,high temperature and high pressure autoclave was used to simulate the thermal recovery environment of 260℃and 1%oxygen partial pressure,and the stress corrosion of 316L hydraulic control pipeline was characterized by SEM and EDS.The results showed that the stress and strain made the passive film of 316L hydraulic control pipeline produce microcracks,which reducing the corrosion resistance of pipeline.In the simulated environment of high temperature and high pressure thermal recovery,oxygen promoted the microcrack to become the small anode,the passive film was the large cathode,and the crack tip autocatalytic developed,which eventually led to stress corrosion cracking of 316L hydraulic control pipeline and multiple parallel circumferential cracks.