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<p>The microstructural evolution of Inconel 617B (referred to as IN 617B) welded joint without and with post weld heat treatment (PWHT) at 980&#xa0;°C after aging at 750&#xa0;°C were systematically investigated by OM, SEM and TEM, and the mechanical properties including hardness, ultimate tensile strength (UTS) and impact toughness were tested. The results show that compared with the IN 617B welded joint with PWHT, the hardness and UTS of that without PWHT are lower before and after short-term aging whereas higher after long-term aging. The impact toughness of IN 617B welded joint without PWHT keeps higher than that of IN 617B welded joint with PWHT before and after aging. PWHT leads to the precipitation of a large number of inter and intragranular M<sub>23</sub>C<sub>6</sub> carbides, whereas the fine <i>γ</i>′ phase precipitates only after aging. In base metal (BM), the intragranular M<sub>23</sub>C<sub>6</sub> carbides precipitate not only on the dislocation lines but also adjacent to <i>γ</i>′ phase particles during aging. In weld metal (WM), the intragranular M<sub>23</sub>C<sub>6</sub> carbides prefer to precipitate in the inter-dendritic regions. The very fine intragranular M<sub>23</sub>C<sub>6</sub> carbides continuously precipitate during the coarsening of formed M<sub>23</sub>C<sub>6</sub> carbides. M<sub>23</sub>C<sub>6</sub> carbides play a vital role in influencing the hardness, UTS and impact toughness of IN 617B welded joint. The increase in the number of fine intragranular M<sub>23</sub>C<sub>6</sub> carbides effectively improves the hardness and UTS, and it obviously deteriorates the impact toughness by decreasing the plasticity at the same time. The formation of large-sized intergranular M<sub>23</sub>C<sub>6</sub> carbides and needle/rod-like intragranular M<sub>23</sub>C<sub>6</sub> carbides is also detrimental to the impact toughness. Consequently, although PWHT at 980&#xa0;°C enhances the hardness and UTS of IN 617B welded joint before and after short-term aging, it restricts the increase in the hardness and UTS by decreasing the number of fine intragranular M<sub>23</sub>C<sub>6</sub> carbides precipitated during aging. Also, it decreases the impact toughness through promoting the precipitation of inter and intragranular M<sub>23</sub>C<sub>6</sub> carbides before aging and increasing the number of coarsened needle/rod-like M<sub>23</sub>C<sub>6</sub> carbides after aging.</p>

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The Effect of High-Temperature Post Weld Heat Treatment on the Microstructure and Mechanical Properties of Inconel 617B Welded Joint After Aging at 750 °C

  • 期刊论文

  • 发表日期：

    2026年2月11日

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  • Renyuan Zhou,
  • Yuhao Wang,
  • Lujie Wang,
  • Xinyao Huang,
  • Yuntong Liu,
  • Lihui Zhu

摘要

The microstructural evolution of Inconel 617B (referred to as IN 617B) welded joint without and with post weld heat treatment (PWHT) at 980 °C after aging at 750 °C were systematically investigated by OM, SEM and TEM, and the mechanical properties including hardness, ultimate tensile strength (UTS) and impact toughness were tested. The results show that compared with the IN 617B welded joint with PWHT, the hardness and UTS of that without PWHT are lower before and after short-term aging whereas higher after long-term aging. The impact toughness of IN 617B welded joint without PWHT keeps higher than that of IN 617B welded joint with PWHT before and after aging. PWHT leads to the precipitation of a large number of inter and intragranular M23C6 carbides, whereas the fine γ′ phase precipitates only after aging. In base metal (BM), the intragranular M23C6 carbides precipitate not only on the dislocation lines but also adjacent to γ′ phase particles during aging. In weld metal (WM), the intragranular M23C6 carbides prefer to precipitate in the inter-dendritic regions. The very fine intragranular M23C6 carbides continuously precipitate during the coarsening of formed M23C6 carbides. M23C6 carbides play a vital role in influencing the hardness, UTS and impact toughness of IN 617B welded joint. The increase in the number of fine intragranular M23C6 carbides effectively improves the hardness and UTS, and it obviously deteriorates the impact toughness by decreasing the plasticity at the same time. The formation of large-sized intergranular M23C6 carbides and needle/rod-like intragranular M23C6 carbides is also detrimental to the impact toughness. Consequently, although PWHT at 980 °C enhances the hardness and UTS of IN 617B welded joint before and after short-term aging, it restricts the increase in the hardness and UTS by decreasing the number of fine intragranular M23C6 carbides precipitated during aging. Also, it decreases the impact toughness through promoting the precipitation of inter and intragranular M23C6 carbides before aging and increasing the number of coarsened needle/rod-like M23C6 carbides after aging.