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<p>A dissimilar weld joint between ferritic P92 steel and austenitic 304L stainless steel was fabricated using the gas tungsten arc welding process with ERNiCr-3 (Inconel 82) nickel-based filler metal. The joint was systematically evaluated through high-temperature tensile and creep testing, supplemented by comprehensive metallographic and micro-analytical investigations, to elucidate the mechanical performance and microstructural degradation mechanisms. Elevated-temperature tensile tests were conducted at 550, 600, 650, and 700&#xa0;°C. A distinct fracture location transition was observed at 650&#xa0;°C: failure shifted from the 304L base metal to the P92 base metal, signifying strong metallurgical bonding and high structural integrity of the weld. The ultimate tensile strength, yield strength, and percentage elongation of the welded joint were benchmarked against the respective base metals, revealing competitive performance. Creep experiments performed at 650&#xa0;°C under the stress in the range of 100-180&#xa0;MPa consistently exhibited rupture in the P92 HAZ/base metal, confirming the superior creep resistance of the joint interface and weld metal. A logarithmic linear regression model was established to predict creep rupture life, expressed as log (t<sub>r</sub>) = 16.605 + (− 6.8) log (σ), enabling reliable extrapolation of creep behavior at extended service conditions. The obtained stress exponent values of 4.5 and 6.8 suggest that the dislocation climb is the rate-controlling mechanism of creep at 650&#xa0;°C within the stress range of 100-180&#xa0;MPa. Detailed fractographic studies using field-emission scanning electron microscopy (FESEM) unveiled the dominant fracture mechanisms, while optical and electron microscopies-based metallography provided insights into microstructural evolution near the fracture location. The findings highlight that the P92/304L dissimilar welds produced with ERNiCr-3 consumables exhibit robust mechanical properties, with failure governed predominantly by the weaker base metals under high-temperature loading. This work provides critical insights into the deformation and fracture behavior of ferritic-austenitic dissimilar joints, contributing to the design of reliable components for ultra-supercritical boilers.</p>

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Understanding Creep Rupture and Fracture Mechanisms in P92/304L Dissimilar Joints

  • 期刊论文

  • 发表日期：

    2025年11月14日

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  • Mudit Maheshwari,
  • Krishna Guguloth,
  • Gaurav Dak,
  • Jaydeep Joshi,
  • Ashish Yadav,
  • Arunsinh Zala,
  • Sachin Sirohi,
  • Chandan Pandey

摘要

A dissimilar weld joint between ferritic P92 steel and austenitic 304L stainless steel was fabricated using the gas tungsten arc welding process with ERNiCr-3 (Inconel 82) nickel-based filler metal. The joint was systematically evaluated through high-temperature tensile and creep testing, supplemented by comprehensive metallographic and micro-analytical investigations, to elucidate the mechanical performance and microstructural degradation mechanisms. Elevated-temperature tensile tests were conducted at 550, 600, 650, and 700 °C. A distinct fracture location transition was observed at 650 °C: failure shifted from the 304L base metal to the P92 base metal, signifying strong metallurgical bonding and high structural integrity of the weld. The ultimate tensile strength, yield strength, and percentage elongation of the welded joint were benchmarked against the respective base metals, revealing competitive performance. Creep experiments performed at 650 °C under the stress in the range of 100-180 MPa consistently exhibited rupture in the P92 HAZ/base metal, confirming the superior creep resistance of the joint interface and weld metal. A logarithmic linear regression model was established to predict creep rupture life, expressed as log (tr) = 16.605 + (− 6.8) log (σ), enabling reliable extrapolation of creep behavior at extended service conditions. The obtained stress exponent values of 4.5 and 6.8 suggest that the dislocation climb is the rate-controlling mechanism of creep at 650 °C within the stress range of 100-180 MPa. Detailed fractographic studies using field-emission scanning electron microscopy (FESEM) unveiled the dominant fracture mechanisms, while optical and electron microscopies-based metallography provided insights into microstructural evolution near the fracture location. The findings highlight that the P92/304L dissimilar welds produced with ERNiCr-3 consumables exhibit robust mechanical properties, with failure governed predominantly by the weaker base metals under high-temperature loading. This work provides critical insights into the deformation and fracture behavior of ferritic-austenitic dissimilar joints, contributing to the design of reliable components for ultra-supercritical boilers.