Abstract: The effect of grain size on 550 ~650 °C 360 〜165 MPa stress rupture property of 316H austenitic stainlees steel 28 mm plate is studued and its rupture mode is analyzed. At 550 °C and by 360 MPa or 335 MPa stress, the stress rupture life of the fine grain (44. 5 μm ) plate only reaches 48. 92% or 51.98% of the coarse grain (89. 6 μm) plate. Wedge crack on the grain boundaries led to the rupture. Tlie grain size has more influence on the stress rupture property, and higher stress makes the effect increase furtherly. However, at 650 °C and by 165 MPa, the stress rupture life of the fine grain (44.5 μm ) plate reaches 91.35% of the coarse grain (89.6 μm)plate. In this case, the grain size has a less influence on the stress rupture property, and microscopic damage occurring during stress-rupture is caused by the growth and coalescence of cavities on grain boundaries.

摘要： 研究了316H奥氏体不锈钢28 mm板晶粒尺寸对550～650℃360～165 MPa持久性能的影响,分析了断裂机理。在温度550℃、应力360 MPa和335 MPa条件下,小晶粒尺寸(44.5μm)钢板的持久断裂时间仅为大晶粒尺寸(89.6μm)钢板的48.92%和51.98%,持久断裂由晶界处楔形裂纹引起,晶粒尺寸对持久性能影响较大,较高的应力会使得晶粒尺寸对持久性能的影响进一步加大;而在温度650℃,应力165 MPa条件下,44.5μm小晶粒钢板的持久断裂时间达到89.6μm大晶粒钢板的91.35%,持久断裂则由晶界空洞的形成长大相互连接引起,晶粒尺寸对持久性能影响较小。