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<p>A multi-cycle quenching and partitioning (MCQ&amp;P) process was applied to a Mn-Si-Al transformation-induced plasticity (TRIP) assisted steel to investigate the microstructural evolution and mechanical behavior. Through repeated thermal cycling, cumulative partitioning of carbon and manganese occurs between intercritical austenite and ferrite. The sequential appearance of primary, secondary and tertiary intercritical ferrite alongside tempered martensite progressively subdivides and refines the intercritical austenite. This evolution yields a heterogeneous ferrite microstructure exhibiting hierarchical gradients in effective grain size, solute concentration, dislocation density and nanohardness. The solute-enriched and dislocation-dense intermediate ferrite phases reconcile the mechanical mismatch between soft and hard phases to prevent interfacial stress concentrations and promote sustained strain accommodation. Meanwhile, more refined, chemically enriched austenite remains stable at room temperature after multi-cycle treatment. Ultimately, the coupled mechanisms in the three-cycle sample to produce a superior strength-ductility synergy (yield strength: 712&#xa0;MPa; ultimate tensile strength: 1083&#xa0;MPa; total elongation: 29.6%), surpasses most TRIP steels at comparable strength levels.</p>

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Hierarchical microstructural heterogeneity in TRIP-assisted steels: achieving superior strength and ductility via multi-cycle quenching and partitioning

  • 期刊论文

  • 发表日期：

    2026年7月22日

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  • Bingyu Yuan,
  • Yunbo Xu,
  • Yijing Gao,
  • Xingxia Hou,
  • Yunzi Yan

摘要

A multi-cycle quenching and partitioning (MCQ&P) process was applied to a Mn-Si-Al transformation-induced plasticity (TRIP) assisted steel to investigate the microstructural evolution and mechanical behavior. Through repeated thermal cycling, cumulative partitioning of carbon and manganese occurs between intercritical austenite and ferrite. The sequential appearance of primary, secondary and tertiary intercritical ferrite alongside tempered martensite progressively subdivides and refines the intercritical austenite. This evolution yields a heterogeneous ferrite microstructure exhibiting hierarchical gradients in effective grain size, solute concentration, dislocation density and nanohardness. The solute-enriched and dislocation-dense intermediate ferrite phases reconcile the mechanical mismatch between soft and hard phases to prevent interfacial stress concentrations and promote sustained strain accommodation. Meanwhile, more refined, chemically enriched austenite remains stable at room temperature after multi-cycle treatment. Ultimately, the coupled mechanisms in the three-cycle sample to produce a superior strength-ductility synergy (yield strength: 712 MPa; ultimate tensile strength: 1083 MPa; total elongation: 29.6%), surpasses most TRIP steels at comparable strength levels.