Study of the structure and properties of the metal of reactor pressure vessel welded joints made of Cr–Mo–V steel in the process of manufacture and operation

Abstract

The paper presents a study of changes in the structure and mechanical properties of the metal of the welded joints of steel 15Cr2МoVА-А mod. A during post weld heat treatment (PWHT) at the reactor pressure vessel (RPV) manufacturing and also as a result of thermal exposure during its operation. It has been established that in as-welded state, the weld metal has a satisfactory level of plastic characteristics and high values of impact strength, but an excessively high level of strength properties. PWHT at 655°C reduces the strength properties, but does not lead to a significant increase of impact strength level. The final properties are formed by PWHT at 670°C. At the indicated temperatures, the low sensitivity of the heat affected zone (HAZ) metal and the base metal to tempering as well as to thermal exposure at 350°C, has been revealed.