Effects of temperature on the local fracture toughness behavior of Chinese SA508-III welded joint

• Published in: Nuclear engineering and technology Vol. 52; no. 8; pp. 1732 - 1741
• Main Authors: Li, Xiangqing, Ding, Zhenyu, Liu, Chang, Bao, Shiyi, Qian, Hao, Xie, Yongcheng, Gao, Zengliang
• Format: Journal Article
• Language: Korean
• Published: 2020
• Subjects: Elevated temperature; Welded joint; Unified J-integral resistance curve; Reactor pressure vessel steel; Fracture toughness
• ISSN: 1738-5733; 2234-358X

The structural integrity of welded joints in the reactor pressure vessel (RPV) is directly related to the safety of nuclear power plants. The RPV is made from SA508-III steel in a pressurized water reactor. In this study, we investigated the effects of temperature on the tensile and fracture toughness properties of Chinese SA508-III welded joint in different sampling areas in order to provide reference data for structural integrity assessments of RPVs. The specimens used in tensile and fracture toughness tests were fabricated from the base metal (BM), weld metal (WM), and the heat-affected zone (HAZ) in the welded joint. The representative testing temperatures included the ambient temperature (20 ℃), upper shelf temperature (100 ℃), and service temperature (320 ℃). The results showed that temperature greatly affected the fracture toughness (JIC) values for the SA508-III welded joint. The JIC values for BM and HAZ both decreased remarkably from 20 ℃ to 320 ℃. The fracture morphologies showed that the BM and HAZ in the welded joint exhibited fully ductile fracture at 20 ℃, whereas partial cleavage fracture was mixed in ductile fracture mode at 100 ℃ and 320 ℃. The WM exhibited the ductile and cleavage fracture mixed mode at various temperatures, and the JIC values showed slight changes.