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<p>The microstructural features of a Fe-21Cr-11Mn-6Ni-0.08C-0.5N high-nitrogen austenitic steel after its quenching and high-temperature thermomechanical treatment (HTMT) by hot rolling are investigated using scanning and transmission electron microscopy (SEM and TEM) and x-ray diffraction (XRD). A local fragmentation of the steel grain structure, with the formation of low- and high-angle misorientation boundaries, and an increased density of dislocation substructures resulting from HTMT are demonstrated. It is revealed that hot plastic deformation is accompanied by dynamic recrystallization (DRX). The average grain size is found to be 10.2&#xa0;µm, approximately four times smaller than in the quenched state. This grain refinement is seen to increase the yield strength up to 1185&#xa0;MPa at − 70&#xa0;°C, 895&#xa0;MPa at 20&#xa0;°C, and 606&#xa0;MPa at 275&#xa0;°C, which is about 1.6, 1.7, and 2.2 times higher than in the quenched state, respectively. At the same time, the elongation to failure remains at a good level (at least 23%) at room and subzero temperatures and at an acceptable level (at least 12%) at 275&#xa0;°C. The ductility values are high at − 70 and 20&#xa0;°C, which is attributed to twinning-induced plasticity (TWIP). At 275&#xa0;°C, twinning was suppressed, and the reduction in ductility was associated with an increased defect density. It is shown that at all tensile test temperatures, the steel mainly exhibits a ductile cup fracture. It is shown that HTMT eliminates or reduces the fraction of intergranular viscous fracture elements, observed in the quenched state at room and subzero temperatures.</p>

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Microstructure and Mechanical Properties of High-Nitrogen Austenitic Steel after High-Temperature Thermomechanical Treatment by Hot Rolling

  • 期刊论文

  • 发表日期：

    2025年11月11日

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  • Igor Litovchenko,
  • Sergey Akkuzin,
  • Nadezhda Polekhina,
  • Anna Kim,
  • Evgeny Moskvichev

摘要

The microstructural features of a Fe-21Cr-11Mn-6Ni-0.08C-0.5N high-nitrogen austenitic steel after its quenching and high-temperature thermomechanical treatment (HTMT) by hot rolling are investigated using scanning and transmission electron microscopy (SEM and TEM) and x-ray diffraction (XRD). A local fragmentation of the steel grain structure, with the formation of low- and high-angle misorientation boundaries, and an increased density of dislocation substructures resulting from HTMT are demonstrated. It is revealed that hot plastic deformation is accompanied by dynamic recrystallization (DRX). The average grain size is found to be 10.2 µm, approximately four times smaller than in the quenched state. This grain refinement is seen to increase the yield strength up to 1185 MPa at − 70 °C, 895 MPa at 20 °C, and 606 MPa at 275 °C, which is about 1.6, 1.7, and 2.2 times higher than in the quenched state, respectively. At the same time, the elongation to failure remains at a good level (at least 23%) at room and subzero temperatures and at an acceptable level (at least 12%) at 275 °C. The ductility values are high at − 70 and 20 °C, which is attributed to twinning-induced plasticity (TWIP). At 275 °C, twinning was suppressed, and the reduction in ductility was associated with an increased defect density. It is shown that at all tensile test temperatures, the steel mainly exhibits a ductile cup fracture. It is shown that HTMT eliminates or reduces the fraction of intergranular viscous fracture elements, observed in the quenched state at room and subzero temperatures.