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采用高温高压慢应变速率拉伸试验方法(SSRT),研究了不同氯离子浓度和饱和氧环境对堆内构件304L焊接件在模拟一回路高温高压硼锂水介质中氯致应力腐蚀开裂的影响。结果表明:随着氯离子含量(1~50mg/L)的增加,304L焊接件应力腐蚀敏感性的一般趋势是增加。当只有氧没有氯离子时,焊接件样品完全为机械韧性断裂,断面氧的含量极低。而饱和氧+氯离子条件时,氯离子的存在显然提高了断面氧的含量。当氯离子的浓度为1~5mg/L时,断面没有观察到脆断区,应力腐蚀敏感性的差异可能主要来自焊接件自身。当氯离子浓度由10mg/L增加到20mg/L时,脆断区面积所占比率由36%增加至48%。进一步增加氯离子浓度至50mg/L时,脆断区面积并没有一直增加,而是稍微有些下降,相应的应力腐蚀敏感性也有些下降。慢应变速率拉伸试验的结果与断面观察的结果一致。能量散射X-射线谱(EDS)分析表明脆断区氧含量明显高于韧窝区,韧窝区表面分布着直径200nm至800nm的氧化物颗粒,较小颗粒呈球形,较大颗粒呈立方体形。
The effect of different chloride ion concentration and saturated oxygen on the stress corrosion cracking induced by chloride in high temperature and high pressure boron-lithium aqueous medium was studied by using high temperature and high pressure slow strain rate tensile test (SSRT). The results show that with the increase of chloride ion content (1 ~ 50mg / L), the general trend of stress corrosion sensitivity of 304L weldments increases. When only oxygen is free of chloride ions, the weldment samples are completely mechanically ductile and have very low cross-sectional oxygen content. Saturated oxygen + chloride ion conditions, the presence of chloride ions obviously increased the cross-section oxygen content. When the chloride ion concentration of 1 ~ 5mg / L, no brittle fracture zone was observed, the sensitivity of stress corrosion may mainly come from the weld itself. When the chloride ion concentration increased from 10mg / L to 20mg / L, the proportion of brittle fracture zone increased from 36% to 48%. When the concentration of chloride ion is further increased to 50mg / L, the area of brittle fracture zone does not increase all the time, but slightly decreases, and the corresponding stress corrosion sensitivity decreases somewhat. The results of the slow strain rate tensile test are consistent with those of the cross-section observation. Energy dispersive X-ray spectroscopy (EDS) analysis showed that the oxygen content in the brittle fracture zone was significantly higher than that in the dimple zone. Oxide particles with a diameter of 200 nm to 800 nm were distributed on the surface of the dimple zone. The smaller particles were spherical and the larger particles were cubic.