在模拟核电一回路高温高压水环境中,采用慢应变速率拉伸试验方法,研究温度对304L不锈钢应力腐蚀开裂的影响规律。通过扫描电镜观察,对试样断口形貌进行分析。结果表明,在高压水环境中,随着温度的升高,材料有向脆性断裂转变的倾向,抗拉强度等参数变化不大,延伸率和断面收缩率略有降低;在研究温度范围内,304L不锈钢试样断口未发现明显脆性解理特征;温度处于200-345℃区间时,没有发现存在304L不锈钢敏感温度,材料应力腐蚀敏感性较低。

In a simulated primary circuit of PWR environment, the effect of temperature on Stress Corrosion Cracking (SCC) of 304L stainless steel in high-temperature and high-pressure water was investigated using Slow Strain Rate Tests (SSRT). And the fracture morphology of specimens was analyzed with the aid of Scanning Electron Microscopy (SEM). The results show that 304L stainless steel tends towards a brittle fracture as temperature increasing. Certain parameters, such as tensile strength, almost remain unchanged, while both elongation and section shrinkage slightly decrease. During the test, no obvious cleavage character is found on the fracture surfaces of 304L stainless steel specimens. With temperature increasing from 200℃ to 345℃, no sensitive temperature is found for 304L stainless steel and the susceptibility to SCC is low.