The objective of this study is to investigate the influence of post weld heat treatment （PWHT） on the distribution of residual stress in welded pipes with large thickness. The detailed pass-by-pass finite element si...The objective of this study is to investigate the influence of post weld heat treatment （PWHT） on the distribution of residual stress in welded pipes with large thickness. The detailed pass-by-pass finite element simulation was developed to study the residual stress in narrow gap multipass welding of pipes with a wall thickness of 150 mm and 89 weld beads. The effect of PWHT on welding residual stress was also investigated by means of numerical analysis. The simulated results show that the hoop stress is tensile stress in the weld region and compressive stress in the parent metal areas adjacent to weld seam. After heat treatment, the residual stresses decrease substantially, and the simulated residual stress is validated by the experimental one. The distribution of the through-wall axial residual stress along the weld center line is a self-equilibrating type.展开更多
The microstractures of 9Cr-lMo multipass deposited metal were observed. The effect of microstructure on impact toughness of 9Cr-lMo multipass deposited metal with varying heat inputs was investigated. Result shows tha...The microstractures of 9Cr-lMo multipass deposited metal were observed. The effect of microstructure on impact toughness of 9Cr-lMo multipass deposited metal with varying heat inputs was investigated. Result shows that fine-grained microstructure occurs in reheated zones. The absorbed energy increases with the increase of volume fraction of fine-grained microstructure , suggesting that the volume fraction of fine-grained microstracture influences directly on impact toughness. The increasing ratio of fine-grained zone thickness to weld layer thickness is responsible for improving impact toughness after PWHT.展开更多
基金The authors acknowledge the financial support of the National Science and Technology Support Program of China （2009BAF44 BO0） and Research Fund for the Doctoral Program of Higher Education of China （20100201110065） and National Natural Science Foundation of China （ 51375370 ）.
文摘The objective of this study is to investigate the influence of post weld heat treatment （PWHT） on the distribution of residual stress in welded pipes with large thickness. The detailed pass-by-pass finite element simulation was developed to study the residual stress in narrow gap multipass welding of pipes with a wall thickness of 150 mm and 89 weld beads. The effect of PWHT on welding residual stress was also investigated by means of numerical analysis. The simulated results show that the hoop stress is tensile stress in the weld region and compressive stress in the parent metal areas adjacent to weld seam. After heat treatment, the residual stresses decrease substantially, and the simulated residual stress is validated by the experimental one. The distribution of the through-wall axial residual stress along the weld center line is a self-equilibrating type.
文摘The microstractures of 9Cr-lMo multipass deposited metal were observed. The effect of microstructure on impact toughness of 9Cr-lMo multipass deposited metal with varying heat inputs was investigated. Result shows that fine-grained microstructure occurs in reheated zones. The absorbed energy increases with the increase of volume fraction of fine-grained microstructure , suggesting that the volume fraction of fine-grained microstracture influences directly on impact toughness. The increasing ratio of fine-grained zone thickness to weld layer thickness is responsible for improving impact toughness after PWHT.
