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<p>High-strength low-alloy (HSLA) steels are widely used in industries requiring superior mechanical properties and weldability; however, their corrosion resistance remains a challenge. To enhance their performance in aggressive environments, stainless steel (SS) weld overlays, specifically SS308L and SS309L, were deposited using the gas tungsten arc welding (GTAW) process. This study investigates the microstructural evolution, hardness variations and corrosion resistance of these weld overlays under different post-weld heat treatment (PWHT) conditions at 600&#xa0;°C for 1&#xa0;h and 10&#xa0;h. Microstructural analysis revealed that as-welded SS308L and SS309L contained interdendritic <i>δ</i>-ferrite, which contributed to enhanced mechanical stability but posed risks of sigma (<i>σ</i>) phase formation upon prolonged heat exposure. Short-term PWHT (1&#xa0;h) led to stress relaxation, minor carbide precipitation and improved corrosion resistance. However, long-term PWHT (10&#xa0;h) promoted <i>δ</i>-ferrite decomposition, sigma phase formation, and chromium carbide precipitation (M23C6), reducing ductility and pitting resistance. Hardness analysis showed a decline in SS308L and SS309L hardness after PWHT, with a more significant reduction observed after 10-h exposure due to microstructural destabilization. Electrochemical corrosion tests confirmed that short-term PWHT improved corrosion resistance, particularly in SS308L, whereas prolonged exposure increased susceptibility to localized corrosion. Overall, this study highlights the importance of optimizing PWHT duration to balance mechanical integrity, hardness retention, and corrosion resistance in weld overlays. These findings enhance the understanding of weld overlay behavior under thermal exposure, contributing to improved reliability and performance in corrosion-critical and mechanically demanding applications such as offshore structures, power generation systems, and chemical processing environments.</p>

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Microstructural and Corrosion Behavior Analysis of GTAW Weld Overlays on High-Strength Low-Alloy Steels

  • 期刊论文

  • 发表日期：

    2025年8月23日

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  • V. Shashikanth,
  • Raffi Mohammed

摘要

High-strength low-alloy (HSLA) steels are widely used in industries requiring superior mechanical properties and weldability; however, their corrosion resistance remains a challenge. To enhance their performance in aggressive environments, stainless steel (SS) weld overlays, specifically SS308L and SS309L, were deposited using the gas tungsten arc welding (GTAW) process. This study investigates the microstructural evolution, hardness variations and corrosion resistance of these weld overlays under different post-weld heat treatment (PWHT) conditions at 600 °C for 1 h and 10 h. Microstructural analysis revealed that as-welded SS308L and SS309L contained interdendritic δ-ferrite, which contributed to enhanced mechanical stability but posed risks of sigma (σ) phase formation upon prolonged heat exposure. Short-term PWHT (1 h) led to stress relaxation, minor carbide precipitation and improved corrosion resistance. However, long-term PWHT (10 h) promoted δ-ferrite decomposition, sigma phase formation, and chromium carbide precipitation (M23C6), reducing ductility and pitting resistance. Hardness analysis showed a decline in SS308L and SS309L hardness after PWHT, with a more significant reduction observed after 10-h exposure due to microstructural destabilization. Electrochemical corrosion tests confirmed that short-term PWHT improved corrosion resistance, particularly in SS308L, whereas prolonged exposure increased susceptibility to localized corrosion. Overall, this study highlights the importance of optimizing PWHT duration to balance mechanical integrity, hardness retention, and corrosion resistance in weld overlays. These findings enhance the understanding of weld overlay behavior under thermal exposure, contributing to improved reliability and performance in corrosion-critical and mechanically demanding applications such as offshore structures, power generation systems, and chemical processing environments.