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Enhancing Mechanical Properties of Carbon–Silicon Steel through Two–Stage Quenching and Partitioning with Bainitic Transformation: Ultimate Tensile Strength of 1875 MPa and Total Elongation of 8.03%

Journal Article · · Steel Research International
 [1];  [2];  [3];  [4];  [2];  [5];  [6];  [7]
  1. Federal Univ. of ABC (UFABC), Santo Andre, SP (Brazil)
  2. Institute for Technological Research, São Paulo (Brazil)
  3. Vale Technological Institute, Ouro Preto, MG (Brazil)
  4. Federal Univ. of Ceara, Fortaleza, CE (Brazil)
  5. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
  6. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
  7. Universidad del Magdalena, Santa Marta (Colombia)
To achieve the desired microstructural properties, the ongoing development and innovation in new structural steels require novel thermal processing. This study aims to improve the mechanical properties of a commercial spring carbon–silicon steel by tailoring its microstructure through a process involving quenching and partitioning (Q&P) followed by bainitic transformation. A two–stage Q&P process is proposed to generate a nanoscale dispersion of stable retained austenite and carbides within the tempered martensite and bainite microstructure. The resulting tensile properties demonstrate a yield strength of 1280 MPa, an ultimate tensile strength of 1875 MPa, and a total elongation of 8.03%. These values surpass those of conventional spring 9254 steel, highlighting the effectiveness of the thermal treatment design. Microstructure analysis reveals the presence of tempered martensite, bainite sheaves, nanoscale carbides, and aggregates of retained austenite. Moreover, the resulting body–centered cubic matrix exhibits minimal lattice tetragonality of ≈1.0051, coupled with stable retained austenite featuring a carbon concentration of ≈3.42 ± 0.5 wt%, resulting in outstanding strength–ductility properties. In conclusion, these findings indicate that the proposed two–stage Q&P process, followed by bainitic transformation, significantly enhances the mechanical properties of carbon–silicon steels, making it a promising candidate for high–performance spring applications.
Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
National Council of Scientific and Technological Development (CNPq); São Paulo Research Foundation (FAPESP); USDOE
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
2438711
Journal Information:
Steel Research International, Journal Name: Steel Research International Journal Issue: 6 Vol. 95; ISSN 1611-3683
Publisher:
WileyCopyright Statement
Country of Publication:
United States
Language:
English

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