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<p>Alloy 617 is widely utilized in critical high-temperature components across advanced ultra-supercritical power plants and very high-temperature reactors<b>.</b> Post-weld heat treatment (PWHT) is known to suppress stress-relaxation cracking in alloy 617, but its specific impact on the mechanical properties of the heat-affected zone (HAZ) has not been investigated. In this study, a Gleeble thermal simulator was utilized to reproduce the simulated HAZ thermal cycles at 750, 1050 and 1320&#xa0;°C, to systematically investigate the influence of PWHT on the microstructure and mechanical properties of these regions. It was revealed that PWHT promoted the formation of continuous M<sub>23</sub>C<sub>6</sub> carbide networks along grain boundaries, increasing the average carbide size from 0.31-0.45&#xa0;μm to 0.55-0.69&#xa0;μm and the area fraction from 1.52-2.44% to 3.82-4.56%. PWHT enhanced the room-temperature ultimate tensile strength (UTS) by approximately 100&#xa0;MPa, while dramatically improving high-temperature (750&#xa0;°C) properties. Yield strength (YS) increased by 33-75% and UTS by 127-156% across HAZ subzones with different peak temperatures. The continuous M<sub>23</sub>C<sub>6</sub> network suppresses grain boundary sliding and dislocation climb at elevated temperatures, thereby driving substantial strengthening. Conversely, the depletion of <i>γ</i>′-forming elements (Cr, Mo) leads to limited intragranular precipitation, thereby restricting the room-temperature strengthening. These findings provide a theoretical foundation and data support for optimizing the alloy 617 PWHT process.</p>

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Effect of Post-weld Heat Treatment on the Microstructure and Mechanical Properties of the Heat-Affected Zone of Alloy 617

  • 期刊论文

  • 发表日期：

    2026年2月25日

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  • Yuxin Wang,
  • Zhaoqing Yang,
  • Yu Gao,
  • Chengning Li,
  • Jing Ma,
  • Yanwen Tao,
  • Shiyu Niu,
  • Zhenwen Yang,
  • Ying Wang

摘要

Alloy 617 is widely utilized in critical high-temperature components across advanced ultra-supercritical power plants and very high-temperature reactors. Post-weld heat treatment (PWHT) is known to suppress stress-relaxation cracking in alloy 617, but its specific impact on the mechanical properties of the heat-affected zone (HAZ) has not been investigated. In this study, a Gleeble thermal simulator was utilized to reproduce the simulated HAZ thermal cycles at 750, 1050 and 1320 °C, to systematically investigate the influence of PWHT on the microstructure and mechanical properties of these regions. It was revealed that PWHT promoted the formation of continuous M23C6 carbide networks along grain boundaries, increasing the average carbide size from 0.31-0.45 μm to 0.55-0.69 μm and the area fraction from 1.52-2.44% to 3.82-4.56%. PWHT enhanced the room-temperature ultimate tensile strength (UTS) by approximately 100 MPa, while dramatically improving high-temperature (750 °C) properties. Yield strength (YS) increased by 33-75% and UTS by 127-156% across HAZ subzones with different peak temperatures. The continuous M23C6 network suppresses grain boundary sliding and dislocation climb at elevated temperatures, thereby driving substantial strengthening. Conversely, the depletion of γ′-forming elements (Cr, Mo) leads to limited intragranular precipitation, thereby restricting the room-temperature strengthening. These findings provide a theoretical foundation and data support for optimizing the alloy 617 PWHT process.