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利用动电位扫描技术和慢应变速率拉伸试验(SSRT)以及扫描电子显微镜(SEM)研究了库尔勒土壤模拟溶液中不同外加阴极电位下X80管线钢焊接接头的应力腐蚀开裂(SCC)行为。结果表明:阴极电位对X80钢焊接接头处的SCC敏感性影响较为明显。拉伸试样全部断裂在焊缝或热影响区。在Ecorr下,金属表面裂纹萌生于点蚀坑,试样开裂为阳极溶解机制。当外加电位为-800 m V至-900 m V时,金属处于阴极保护电位区,此时金属的SCC敏感性较低,其开裂机制为阳极溶解和氢致开裂混合机制。当外加电位小于等于-950 m V时,外加电位越低,材料的SCC敏感性越大,此时金属SCC行为表现为氢脆机制。
The stress corrosion cracking (SCC) behavior of welded joints of X80 pipeline steel with different applied cathodic potentials in Korla soil simulated solution was studied by potentiodynamic scanning, slow strain rate tensile test (SSRT) and scanning electron microscopy (SEM). The results show that the cathode potential affects the SCC sensitivity of X80 steel welded joint obviously. Tensile specimens are all fractured in the weld or heat affected zone. Under Ecorr, metal surface cracks originate in the pits and the sample cracks to anodic dissolution mechanism. When the applied potential is -800 mV to -900 mV, the metal is in the cathodic protection potential region. At this time, the metal has a lower SCC sensitivity and the cracking mechanism is a mixed solution of anodic dissolution and hydrogen induced cracking. When the applied potential is less than or equal to -950 mV, the lower the applied potential, the greater the SCC sensitivity of the material. In this case, the metal SCC behaves as a hydrogen embrittlement mechanism.