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<p>Optimizing welding and heat treatment strategies is crucial for P91 steel to ensure a balance between mechanical integrity and corrosion behavior in power plant applications. This study investigates the influence of post-weld conditions—as-welded, post-weld heat treatment (PWHT), and post-weld normalizing and tempering (PWNT)—on the microstructure, mechanical properties, and hot corrosion behavior of P91 welds. These welds are fabricated using the shielded metal arc welding process (SMAW) using E9015-B9 electrodes. PWHT (760&#xa0;°C, 2&#xa0;h) refined the microstructure and improved tensile strength (665.1&#xa0;MPa) and elongation (22.4%) but led to coarser grains in CGHAZ. PWNT resulted in a uniform microstructure with fine MX precipitates, improving impact toughness (83&#xa0;J). Microhardness was the lowest in the weld center, with PWHT providing uniform hardness distribution. Hot corrosion testing in a molten salt environment (50% Na<sub>2</sub>SO<sub>4</sub> + 50% NaCl) revealed superior corrosion resistance in the as-welded specimen (241&#xa0;mg/cm<sup>2</sup> weight gain over 50 cycles), while PWHT and PWNT specimens formed porous oxide scales, increasing corrosion susceptibility. SEM-EDS analysis confirmed Cr-rich spinel (FeCr<sub>2</sub>O<sub>4</sub>) oxides in the as-welded specimen, enhancing oxidation resistance, whereas PWHT and PWNT specimens suffered chloride-induced degradation. While PWHT improves mechanical properties, it compromises hot corrosion resistance, making as-welded specimens more suitable for high-temperature applications. Optimizing heat treatment parameters is crucial for achieving an optimal balance between strength and oxidation resistance in P91 welds.</p>

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Mechanical Integrity and Hot Corrosion Behavior of P91 Welds: Influence of Post-Weld Heat Treatment

  • 期刊论文

  • 发表日期：

    2025年10月8日

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  • Shivendra Singh,
  • Sumit Mahajan,
  • Anup Kumar Maurya,
  • Rahul Chhibber

摘要

Optimizing welding and heat treatment strategies is crucial for P91 steel to ensure a balance between mechanical integrity and corrosion behavior in power plant applications. This study investigates the influence of post-weld conditions—as-welded, post-weld heat treatment (PWHT), and post-weld normalizing and tempering (PWNT)—on the microstructure, mechanical properties, and hot corrosion behavior of P91 welds. These welds are fabricated using the shielded metal arc welding process (SMAW) using E9015-B9 electrodes. PWHT (760 °C, 2 h) refined the microstructure and improved tensile strength (665.1 MPa) and elongation (22.4%) but led to coarser grains in CGHAZ. PWNT resulted in a uniform microstructure with fine MX precipitates, improving impact toughness (83 J). Microhardness was the lowest in the weld center, with PWHT providing uniform hardness distribution. Hot corrosion testing in a molten salt environment (50% Na2SO4 + 50% NaCl) revealed superior corrosion resistance in the as-welded specimen (241 mg/cm2 weight gain over 50 cycles), while PWHT and PWNT specimens formed porous oxide scales, increasing corrosion susceptibility. SEM-EDS analysis confirmed Cr-rich spinel (FeCr2O4) oxides in the as-welded specimen, enhancing oxidation resistance, whereas PWHT and PWNT specimens suffered chloride-induced degradation. While PWHT improves mechanical properties, it compromises hot corrosion resistance, making as-welded specimens more suitable for high-temperature applications. Optimizing heat treatment parameters is crucial for achieving an optimal balance between strength and oxidation resistance in P91 welds.