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<p>In high-end equipment manufacturing, the requirements for welding deformation control have become increasingly stringent. With the development of large-scale heat treatment facilities, post-weld heat treatment (PWHT) of welded components without fixture removal has been gradually adopted. This study systematically investigates the effects of fixture constraints on stress control and deformation suppression throughout the welding and PWHT processes. Thermo-mechanical coupled finite element analysis covering the entire welding-PWHT process was conducted for typical butt and fillet joints in thin-walled box structures under different constraint conditions. The thermal expansion effect of the steel structural frame fixtures during PWHT was explicitly incorporated into the boundary conditions to reproduce the realistic constraint evolution at elevated temperatures. The results indicate that while fixture constraints effectively suppress welding deformation, they also lead to elevated overall residual stress. However, the higher residual stress induced by fixture constraints can be effectively released through creep during PWHT. After PWHT with fixtures, the average stress relief rates of butt and fillet joints reach 61.48% and 60.07%, respectively, both higher than those under fixture-free conditions, resulting in minimal elastic rebound after constraint removal. The welding-PWHT process with fixture constraints therefore achieves synergistic optimization of deformation control and stress relief. These findings clarify the coupled mechanism of fixture constraints on stress evolution and deformation control throughout the welding-PWHT process, and provide theoretical guidance for the optimization of welding and PWHT processes of thin-walled structures in high-end equipment manufacturing.</p>

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Effect of fixturing on stress and deformation in thin-walled joint welding-PWHT

  • 期刊论文

  • 发表日期：

    2026年7月6日

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  • Huadong Lu,
  • Chun Zhang,
  • Guoyang Guan,
  • Yuxi Ding,
  • Kaijian Li,
  • Zimeng Yong

摘要

In high-end equipment manufacturing, the requirements for welding deformation control have become increasingly stringent. With the development of large-scale heat treatment facilities, post-weld heat treatment (PWHT) of welded components without fixture removal has been gradually adopted. This study systematically investigates the effects of fixture constraints on stress control and deformation suppression throughout the welding and PWHT processes. Thermo-mechanical coupled finite element analysis covering the entire welding-PWHT process was conducted for typical butt and fillet joints in thin-walled box structures under different constraint conditions. The thermal expansion effect of the steel structural frame fixtures during PWHT was explicitly incorporated into the boundary conditions to reproduce the realistic constraint evolution at elevated temperatures. The results indicate that while fixture constraints effectively suppress welding deformation, they also lead to elevated overall residual stress. However, the higher residual stress induced by fixture constraints can be effectively released through creep during PWHT. After PWHT with fixtures, the average stress relief rates of butt and fillet joints reach 61.48% and 60.07%, respectively, both higher than those under fixture-free conditions, resulting in minimal elastic rebound after constraint removal. The welding-PWHT process with fixture constraints therefore achieves synergistic optimization of deformation control and stress relief. These findings clarify the coupled mechanism of fixture constraints on stress evolution and deformation control throughout the welding-PWHT process, and provide theoretical guidance for the optimization of welding and PWHT processes of thin-walled structures in high-end equipment manufacturing.