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对泄漏的凝汽器不锈钢管进行了宏观检查、金相检验、和扫描电镜及能谱测试,结果发现管内壁残留有含氯垢及水迹,在长期静态下造成局部浓缩;不锈钢板经过轧制或卷制后,内部有周向残余拉应力。在局部浓缩的腐蚀介质和管子周向的拉应力共同作用下,管内壁表面的氧化膜被腐蚀而破坏,破坏的表面和未破坏的表面分别形成阳极和阴极,阳极处的金属成为离子而被溶解,产生电流流向阴极。由于阳极面积比阴极的小得多,阳极的电流密度很大,进一步腐蚀已破坏的表面。加上拉应力的作用,破坏处逐渐形成裂纹,裂纹随时间逐渐扩展直到管子泄露。
The leaking condenser stainless steel tube macroscopic examination, metallographic examination, and scanning electron microscopy and energy spectrum test found that the inner wall of the tube containing chlorine scale and water traces in the long-term static caused by local concentration; stainless steel plate after rolling After the system or rolling, the internal residual circumferential tensile stress. Under the action of partially concentrated corrosive medium and tensile stress in the circumferential direction of the pipe, the oxide film on the inner wall surface of the pipe is eroded and destroyed, the destroyed surface and the undamaged surface form the anode and the cathode, respectively, and the metal at the anode becomes ionized Dissolved, resulting in current flow to the cathode. Since the anode area is much smaller than the cathode, the current density of the anode is large, further corroding the destroyed surface. Coupled with the role of tensile stress, cracks gradually form cracks, cracks gradually expand over time until the pipe leaks.