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采用慢应变速率试验(SSRT)、扫描电镜(SEM)观察研究了国产X80管线钢焊接接头在0.5mol/LNa2CO3+1mol/LNaHCO3溶液中的应力腐蚀开裂(SCC)敏感性。结果表明,拉伸试样全部断裂在焊缝或热影响区。在所研究的电位区间,拉伸试样随着外加电位正向增加,断面收缩率、断裂时间和断后伸长率增加,而断口部位的裂纹平均扩展速率减小,SCC敏感性降低。试样断口形貌在阴极电位条件下呈准解理断裂,在自腐蚀电位和阳极电位条件下,焊缝试样断口主要是韧性断裂。应力腐蚀机理可以用阳极溶解理论和氢致破裂来解释。
The stress corrosion cracking (SCC) sensitivity of the domestic welded joints of X80 pipeline steel in 0.5 mol / L Na 2 CO 3 + 1 mol / L NaHCO 3 solution was investigated by slow strain rate test (SSRT) and scanning electron microscope (SEM) The results show that all tensile specimens are fractured in the weld or heat affected zone. In the potential range studied, with the increase of the applied potential, the tensile test specimens increased the area shrinkage, the fracture time and the elongation at break, while the average crack growth rate at the fracture site decreased and the SCC sensitivity decreased. The fracture morphology of the specimen shows quasi-cleavage fracture under the condition of cathodic potential. Fracture of the weld specimen is mainly ductile fracture under self-corrosion potential and anodic potential. Stress corrosion mechanisms can be explained by anodic dissolution theory and hydrogen-induced cracking.