The demonstration fast reactor is the first sodium cooled fast reactor power plant in China.Its main steam pipeline is designed with a pressure of 17 MPa and a temperature of 530℃,which belongs to high-temperature and high-pressure pipelines.Considering that there is currently no clear standard specification requirement for the supervision of high-temperature pipelines in nuclear power plants,the metal supervision requirements of high-temperature P91 pipelines are studied based on the problems that occur during the welding and heat treatment process of P91 steel.By analyzing the common heat treatment problems that occur during the welding process of P91 steel,it was found that when the tempering temperature is too high,martensite decomposition and carbide aggregation occur at the welding site,leading to high hardness of the welded joint.When the preheating temperature and interlayer temperature are too high,it will extend the time for the weld seam to cool from 800℃to 500℃and reduce the toughness of the welded joint.Meanwhile,improper operation during the welding process of P91 steel can lead to a decrease in the mechanical properties of the welded joints.Therefore,the welding and post weld heat treatment of P91 steel must undergo strict process evaluation and be qualified before implementation.In addition,during the in-service phase,metal supervision should strengthen the means of hardness testing and metallographic testing,establish a weld seam testing database,and then determine whether the mechanical properties of P91 weld metal have changed.
关键词
钠冷快堆/P91钢/热处理/金属监督
Key words
sodium cooled fast reactor/P91 steel/heat treatment/metal supervision
维普
万方数据