316NG焊接接头在含氯离子的高温高压水中应力腐蚀开裂研究

发布时间：2018-05-14 17:18

  本文选题：NG焊接接头 + 应力腐蚀开裂(SCC)　； 参考：《核动力工程》2017年01期

【摘要】：通过慢应变速率拉伸(SSRT)试验和高温电化学相结合的方法,研究外加电位对奥氏体不锈钢316NG焊接接头在含氯离子的高温高压水中应力腐蚀开裂(SCC)倾向的影响。试验结果表明:退火态316NG焊接接头SCC敏感性随外加电极电位升高而增大,且存在一个介于+50~+100 mV[相对标准氢电极(vs.SHE)]之间的SCC临界电位;低于该电位时,SCC敏感性较小,无明显沿晶开裂,仅断口边缘处存在少量穿晶开裂,随电极电位变化不明显;高于该临界电位时,SCC敏感性急剧增加,并出现明显的沿晶开裂。此外,高温Ar和腐蚀性低(电极电位≤50 mV)的环境中,焊接接头的断裂为力学主导的塑形开裂,其与焊接接头的硬度分布密切相关,硬度越低,越容易断裂;强腐蚀性(电极电位50 mV)环境中,焊接接头的断裂为腐蚀主导的脆性开裂;显然,焊缝及热影响区的SCC敏感性高于母材。
[Abstract]:The effect of applied potential on the stress corrosion cracking (SCC) tendency of austenitic stainless steel 316NG welded joints in high temperature and high pressure water containing chloride ions was studied by means of slow strain rate tensile test and high temperature electrochemical method. The experimental results show that the SCC sensitivity of annealed 316NG welded joints increases with the increase of the applied electrode potential, and there exists a critical SCC potential between 50 ~ 100mV [relative to the standard hydrogen electrode vs.Shee]. There was no obvious intergranular cracking, only a small amount of transgranular cracking occurred at the edge of the fracture surface, which did not change significantly with the electrode potential, and the sensitivity of SCC increased sharply when the critical potential was higher than the critical potential, and obvious intergranular cracking occurred. In addition, in the environment of high temperature ar and low corrosion (electrode potential 鈮，

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