Issue 29

L. Zhao et alii, Frattura ed Integrità Strutturale, 29 (2014) 410-418; DOI: 10.3221/IGF-ESIS.29.36 410 Numerical investigation on stress corrosion cracking behavior of dissimilar weld joints in pressurized water reactor plants Lingyan Zhao School of Science, Xi’an University of Science and Technology, Xi’an 710054, China zhlyan7878@163.com He Xue School of Mechanical Engineering, Xi’an University of Science and Technology, Xi’an 710054, China Xue_he@hotmail.com Fuqiang Yang School of Science, Xi’an University of Science and Technology, Xi’an 710054, China yang_afreet@163.com Yaohong Suo School of Science, Xi’an University of Science and Technology, Xi’an 710054, China yaohongsuo@126.com A BSTRACT . There have been incidents recently where stress corrosion cracking (SCC) observed in the dissimilar metal weld (DMW) joints connecting the reactor pressure vessel (RPV) nozzle with the hot leg pipe. Due to the complex microstructure and mechanical heterogeneity in the weld region, dissimilar metal weld joints are more susceptible to SCC than the bulk steels in the simulated high temperature water environment of pressurized water reactor (PWR). Tensile residual stress (RS), in addition to operating loads, has a great contribution to SCC crack growth. Limited experimental conditions, varied influence factors and diverging experimental data make it difficult to accurately predict the SCC behavior of DMW joints with complex geometry, material configuration, operating loads and crack shape. Based on the film slip/dissolution oxidation model and elastic-plastic finite element method (EPFEM), an approach is developed to quantitatively predict the SCC growth rate of a RPV outlet nozzle DMW joint. Moreover, this approach is expected to be a pre-analytical tool for SCC experiment of DMW joints in PWR primary water environment. K EYWORDS . Dissimilar metal weld; Stress corrosion cracking; Residual stress; Crack growth rate. I NTRODUCTION issimilar metal weld (DMW) joints are widely used to connect the low alloy steel (LAS) nozzles to austenitic stainless steel (SS) pipes in primary water systems of pressurized water reactors (PWR). To form a DMW joint, nickel-based alloy is generally pre-deposited on the ferritic reactor pressure vessel (RPV) nozzle face firstly, then D