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<p>Duplex stainless steels (DSSs) are widely used in the energy and chemical industries due to their favorable combination of mechanical strength and corrosion resistance. However, long-term thermal aging can degrade their performance by inducing microstructural changes, particularly in the ferrite phase. In this study, the deformation behavior of DSSs thermally aged at 475&#xa0;°C for 400, 1000, and 3000&#xa0;hours was investigated using <i>in situ</i> synchrotron Wide-Angle X-ray Scattering (WAXS) tensile testing, with calculated dislocation densities validated by post-mortem Transmission Electron Microscopy (TEM) analysis. Macroscopic tensile results show that thermal aging increases the ultimate tensile strength (UTS) and reduces ductility, with the UTS plateauing after 1000&#xa0;hours. Phase-specific analysis reveals that austenite maintains a stable mechanical response with minimal change in lattice strain and yield strength (~194&#xa0;MPa), while ferrite exhibits pronounced aging effects, including increased lattice strain, progressive hardening up to ~ 1837&#xa0;MPa, and enhanced dislocation multiplication. Load partitioning becomes increasingly asymmetric with aging, shifting more stress to ferrite and intensifying interfacial constraints. And microstructural characterization further shows that long-term aging promotes pore formation at austenite–ferrite boundaries, contributing to earlier fracture and reduced ductility. Together, the <i>in situ</i> WAXS and TEM results provide a mechanistic understanding of how thermal aging selectively alters the ferrite response, driving embrittlement in DSSs.</p>

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Understand the Thermal Aging Effect on Mechanical Response of a Duplex Stainless Steel by In Situ Synchrotron Wide-Angle X-Ray Scattering

  • 期刊论文

  • 发表日期：

    2026年2月18日

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  • Yu Lu,
  • Yiren Chen,
  • Jeffrey Terry,
  • Yong Yang

摘要

Duplex stainless steels (DSSs) are widely used in the energy and chemical industries due to their favorable combination of mechanical strength and corrosion resistance. However, long-term thermal aging can degrade their performance by inducing microstructural changes, particularly in the ferrite phase. In this study, the deformation behavior of DSSs thermally aged at 475 °C for 400, 1000, and 3000 hours was investigated using in situ synchrotron Wide-Angle X-ray Scattering (WAXS) tensile testing, with calculated dislocation densities validated by post-mortem Transmission Electron Microscopy (TEM) analysis. Macroscopic tensile results show that thermal aging increases the ultimate tensile strength (UTS) and reduces ductility, with the UTS plateauing after 1000 hours. Phase-specific analysis reveals that austenite maintains a stable mechanical response with minimal change in lattice strain and yield strength (~194 MPa), while ferrite exhibits pronounced aging effects, including increased lattice strain, progressive hardening up to ~ 1837 MPa, and enhanced dislocation multiplication. Load partitioning becomes increasingly asymmetric with aging, shifting more stress to ferrite and intensifying interfacial constraints. And microstructural characterization further shows that long-term aging promotes pore formation at austenite–ferrite boundaries, contributing to earlier fracture and reduced ductility. Together, the in situ WAXS and TEM results provide a mechanistic understanding of how thermal aging selectively alters the ferrite response, driving embrittlement in DSSs.