高强管线钢在高pH环境中的慢应变拉伸试验研究

Study of Slow Strain Rate Testing for High Strength Pipeline Steels in High pH Environment

通过对国产X80管线钢在高pH环境下慢应变速率拉伸试验(SSRT)研究,分析了国产X80管线钢在0.5 mol/L Na2CO3+1 mol/L NaHCO3溶液中的应力腐蚀破裂(SCC)敏感性,并对其破裂断口进行SEM观察和分析。外加电位时,X80管线钢在高pH溶液中SSRT试验结果表明,随着外加电位的负向增大,X80管线钢的断裂时间tf、延伸率δ和断面收缩率RA明显降低,而裂纹扩展速率CGR增加,SCC敏感性增加。在阴极电位条件下断口呈准解理断裂,断口处有明显的应力腐蚀破裂发生,在自腐蚀电位和阳极电位条件下,X80钢试样断口主要是韧性断裂,SCC敏感性很低。

The susceptibility to stress corrosion cracking （SCC） of the home - made X80 pipeline steel in solution of 0.5 mol/L Na2CO3 and 1 mol/L NaHCO3 was investigated through the study of slow strain rate testing （SSRT） for X80 pipeline steel in high pH environment. The surface of fracture was observed and analyzed by scanning electron microscopy （SEM）. The results showed that the general tendency in the studied potential range was that with negative increasing of potential, fracture time （tf）, elongation （δ） and reduction in area （ RA ） of specimens decreased; mean crack growth rate of SCC and the susceptibility to SCC increased. At cathodic potentials, quasi - cleavage fracture was presented and obvious stress corrosion cracking was observed in the fracture area of specimens. At open circuit potential and anodic potential, ductile fracture was the main fracture pattern and the susceptibility to SCC was very low.