沉淀硬化马氏体不锈钢热老化脆化的热电势检测研究

Study on Thermoelectric Power Measurement to Thermal Aging Effect of Precipitation-Hardened Martensitic Stainless Steel

研究了17-4PH沉淀硬化马氏体不锈钢在400℃下不同时效时间力学性能和热电势变化规律,提出了热电势和冲击韧性的经验公式,并通过在核电厂服役13 a的主蒸汽隔离阀阀杆进行验证。验证结果显示,随着时效时间的延长,材料的冲击韧性下降,屈服强度、抗拉强度和硬度升高,断面收缩率和断裂伸长率下降。材料的热电势变化与冲击韧性呈现指数相关性,材料的屈服强度、抗拉强度、硬度和热电势呈现出较好的线性关系。通过热电势检测评估的冲击韧性和实测值显示出较好的符合性。

The change of mechanical properties and thermoelectric power with the extension of ageing time on the type 17-4 PH precipitation-hardened martensitic stainless steel at 400℃ was studied. An empirical formula for the relationship between thermoelectric power and impact toughness was put forward and verified by the main steam isolation valve stem that has been in service for 13 years in a nuclear power plant. Results indicated that with the extension of aging time, the impact toughness of the material decreases, and the yield strength, tensile strength and hardness increase, and the shrinkage of the section and elongation of the crack decrease. The change of the thermoelectric power of the material was exponential correlation with the impact toughness, and the yield strength, tensile strength, hardness and thermoelectric power of the material show a good linear relationship. Good agreement was observed between impact toughness evaluated by thermoelectric power measurement and laboratory test value.