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<p>The hot-rolled T4003 ferritic stainless steel was subjected to annealing treatments at 700, 820, and 900&#xa0;°C respectively. Optical microscopy (OM), field emission scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS) were utilized to investigate microstructure, precipitation behavior, mechanical properties, and evolution of strengthening mechanisms of the test steel at different annealing temperatures. The results indicate that as the annealing temperature increases from 700 to 900&#xa0;°C, the deformed microstructure of the test steel gradually undergoes recovery and recrystallization. The average grain size initially decreases and then increases, reaching a minimum at 820&#xa0;°C. The dislocation density exhibits a three-stage variation of “decreasing-increasing-decreasing”. The main precipitated phase in the test steel is (Nb,Ti)(C,N) composite carbonitride, whose mass fraction decreases from 0.197 to 0.019 wt.% at 700-820&#xa0;°C, and then increases to 0.074 wt.% due to the supersaturated precipitation induced by <i>γ</i> → <i>α</i> reverse phase transformation at 820-900&#xa0;°C. The particle size first fines and then coarsens. As the annealing temperature increases, the yield strength rises from 285 to 420&#xa0;MPa, the tensile strength increases from 450 to 510&#xa0;MPa, and the elongation after fracture decreases from 35.6 to 20.5%. Quantitative calculation of the strengthening mechanism indicates that grain refinement contributes the most (over 44%), followed by solid solution strengthening (over 15%). Both of them first increase and then decrease. At 860-900&#xa0;°C, the contribution rate of precipitation strengthening increases to 14.8-19.1%, while the contribution of dislocation strengthening can be neglected. When annealed at 820&#xa0;°C, T4003 ferritic stainless steel undergoes complete recrystallization and exhibits the grain refinement genetic effect of <i>γ</i> → <i>α</i> reverse phase transformation, resulting in the elimination of banded structures, random grain orientation, and an optimal strength-toughness combination. Therefore, 820&#xa0;°C is the optimal annealing temperature for this steel grade.</p>

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Effect of Annealing Temperature on the Precipitation Characteristics and Multi Mechanism Strengthening in T4003 Ferritic Stainless Steel

  • 期刊论文

  • 发表日期：

    2026年5月13日

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  • Jie Sheng,
  • Yingjun Liang,
  • Xingchang Tang,
  • Yang Hui,
  • Xuefeng Lu,
  • Changbo Wang,
  • Yufeng Li

摘要

The hot-rolled T4003 ferritic stainless steel was subjected to annealing treatments at 700, 820, and 900 °C respectively. Optical microscopy (OM), field emission scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS) were utilized to investigate microstructure, precipitation behavior, mechanical properties, and evolution of strengthening mechanisms of the test steel at different annealing temperatures. The results indicate that as the annealing temperature increases from 700 to 900 °C, the deformed microstructure of the test steel gradually undergoes recovery and recrystallization. The average grain size initially decreases and then increases, reaching a minimum at 820 °C. The dislocation density exhibits a three-stage variation of “decreasing-increasing-decreasing”. The main precipitated phase in the test steel is (Nb,Ti)(C,N) composite carbonitride, whose mass fraction decreases from 0.197 to 0.019 wt.% at 700-820 °C, and then increases to 0.074 wt.% due to the supersaturated precipitation induced by γ → α reverse phase transformation at 820-900 °C. The particle size first fines and then coarsens. As the annealing temperature increases, the yield strength rises from 285 to 420 MPa, the tensile strength increases from 450 to 510 MPa, and the elongation after fracture decreases from 35.6 to 20.5%. Quantitative calculation of the strengthening mechanism indicates that grain refinement contributes the most (over 44%), followed by solid solution strengthening (over 15%). Both of them first increase and then decrease. At 860-900 °C, the contribution rate of precipitation strengthening increases to 14.8-19.1%, while the contribution of dislocation strengthening can be neglected. When annealed at 820 °C, T4003 ferritic stainless steel undergoes complete recrystallization and exhibits the grain refinement genetic effect of γ → α reverse phase transformation, resulting in the elimination of banded structures, random grain orientation, and an optimal strength-toughness combination. Therefore, 820 °C is the optimal annealing temperature for this steel grade.