Modeling of hardness and welding residual stress in Type 316 stainless steel components for the assessment of stress corrosion cracking

応力腐食割れの評価のためのSUS316ステンレス鋼溶接接手における硬さ及び溶接残留応力のモデル化

Li, S.  ; 山口 義仁 ; 勝山 仁哉  ; Li, Y. ; Deng, D.*

Li, S.; Yamaguchi, Yoshihito; Katsuyama, Jinya; Li, Y.; Deng, D.*

In this work, a framework was proposed on the comprehensive assessment of hardness and welding residual stress in Type 316 austenitic stainless steel welded joints. Firstly, an 8-pass butt-welded joint made of Type 316 stainless steel was fabricated. Finite element analysis of the welded joint was performed to investigate hardness and welding residual stress distributions. The grain growth model was developed for the hardness prediction. The Chaboche combined isotropic-kinematic strain hardening model and time-temperature dependent annealing model were adopted. The relationships between the Vickers hardness and the uniaxial plastic strain as well as grain size were collected from published literatures. The simulation results of the grain size and accumulated equivalent plastic strain were used for the hardness prediction of the welded joint. The predicted hardness was compared with the experimental data of hardness mapping. The distribution of welding residual stress on the outer surface of the welded pipe was measured by using the X-ray diffraction method and strain gauge method, respectively. The predicted welding residual stresses were compared with the measurements. The results obtained showed that the developed numerical approach can predict the hardness and welding residual stress of Type 316 stainless steel welded joints with satisfactory accuracy. The effects of structural constraint and heat input on the hardness and welding residual stress will be investigated as further works, as described in the proposed framework.