目的 研究304L不锈钢在高温高压水蒸气中的应力腐蚀开裂行为及机理。方法 采用慢应变速率试验分别研究了304L不锈钢在常温常压水、高温高压水、高温高压水蒸气环境中的应力腐蚀开裂行为。利用SEM、三维立体显微镜和XPS，分析试样氧化后断口区域的形貌及元素分布。结果 304L不锈钢在常温常压水中的抗拉强度为730 MPa，拉伸率为94.32%。在高温高压水、高温高压水蒸气环境中的抗拉强度分别为382、379 MPa，拉伸率分别为44.98%、47.38%。304L不锈钢在三种试验环境中慢拉伸后的断口表面布满大量韧窝，断口全貌呈韧性断裂特征，高温高压水、高温高压水蒸气中试样的抗拉强度较常温常压水中明显下降。304L不锈钢在高温高压水环境和水蒸气环境中得到的XPS谱图中各结合能峰位置几乎相同，峰的相对强度因载荷的不同而发生变化。施加载荷后，在高温高压水环境中304L不锈钢表面氧化物中的Cr含量增加，而在高温高压水蒸气环境中的Cr含量略有下降。结论304L不锈钢在高温高压水和高温高压水蒸气环境中具有相似的最大抗拉强度和最大应变值。施加载荷将影响304L不锈钢氧化过程中金属元素扩散的速度，进而影响氧化产物的成分。

The stress corrosion cracking behavior and mechanism of 304L stainless steel in high temperature and high pressure water vapor were studied. Stress strain curve measured by means of slow strain rate tests of 304L stainless steel in various conditions; SEM, 3D Stereo Light microscope and XPS were used to analyze the morphology and element distribution of the fracture area of the sample after oxidation. The tensile strength of 304L stainless steel in normal temperature and pressure water was 730 MPa, and the tensile rate is 94.32%. The tensile strength in high temperature and high pressure water/steam environment was 382 MPa and 379 MPa, respectively, and the tensile rate was 44.98% and 47.38%. The fracture surface of 304L stainless steel after slow stretching was covered with a large number of dimples in three test environments. The positions of the binding energy peaks of 304L stainless steel in the XPS spectra obtained in the high temperature and high pressure water environment and the water vapor environment were almost the same, and the relative intensity of the peaks changed due to different loads. The content of Cr in the surface oxide of 304L stainless steel increased in the high temperature and high pressure water environment, while it decreases slightly in the high temperature and high pressure water vapor environment, after loading. The maximum tensile strength and maximum strain value was familiar in high temperature and high pressure water environment as well as the high temperature and high pressure vapor environment. The diffusion rate of metal elements in 304L stainless steel during high temperature oxidation was affected by additional loading. The composition of the oxidation product on the sample surface changed because of the effect of loading.