Microstructure-Based Modelling of Flow and Fracture Behavior of Tailored Microstructures of Ductibor<sup>®</sup> 1000-AS Steel
Emerging grades of press-hardening steels such as Ductibor<sup>®</sup> 1000-AS are now commercially available for use within tailor-welded blanks (TWBs) to enhance ductility and energy absorption in hot-stamped automotive structural components. This study examines the constitutive (harde...
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| Format: | Article |
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MDPI AG
2022-10-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/12/10/1770 |
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| author | Pedram Samadian Armin Abedini Clifford Butcher Michael J. Worswick |
| author_facet | Pedram Samadian Armin Abedini Clifford Butcher Michael J. Worswick |
| author_sort | Pedram Samadian |
| collection | DOAJ |
| description | Emerging grades of press-hardening steels such as Ductibor<sup>®</sup> 1000-AS are now commercially available for use within tailor-welded blanks (TWBs) to enhance ductility and energy absorption in hot-stamped automotive structural components. This study examines the constitutive (hardening) response and fracture limits of Ductibor<sup>®</sup> 1000-AS as functions of the as-quenched microstructure after hot stamping. Three different microstructures consisting of bainite and martensite were obtained by hot stamping with die temperatures of 25 °C, 350 °C, and 450 °C. Mechanical characterization was performed to determine the hardening curves and plane-stress fracture <i>loci</i> for the different quench conditions (cooling rates). Uniaxial-tension and shear tests were conducted to experimentally capture the hardening response to large strain levels. Shear, conical hole-expansion, plane-strain notch tension, and Nakazima tests were carried out to evaluate the stress-state dependence of fracture. A mean-field homogenization (MFH) scheme was applied to model the constitutive and fracture behavior of the mixed-phase microstructures. A dislocation-based hardening model was adopted for the individual phases, which accounts for material chemistry, inter-phase carbon partitioning, and dislocation evolution. The per-phase fracture modelling was executed using a phenomenological damage index based upon the stress state within each phase. The results revealed that the 25 °C hot-stamped material condition with a fully martensite microstructure exhibited the highest level of strength and the lowest degree of ductility. As bainite was formed in the final microstructure by quenching at higher die temperatures, the strength decreased, while the ductility increased. The predicted constitutive and fracture responses in the hot-stamped microstructures were in line with the measured data. Accordingly, the established numerical strategy was extended to predict the mechanical behavior of Ductibor<sup>®</sup> 1000-AS for a broad range of intermediate as-quenched microstructures. |
| first_indexed | 2024-03-09T19:47:21Z |
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| language | English |
| last_indexed | 2024-03-09T19:47:21Z |
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| series | Metals |
| spelling | doaj.art-7e1736689db749c995152fa76bb8773d2023-11-24T01:20:28ZengMDPI AGMetals2075-47012022-10-011210177010.3390/met12101770Microstructure-Based Modelling of Flow and Fracture Behavior of Tailored Microstructures of Ductibor<sup>®</sup> 1000-AS SteelPedram Samadian0Armin Abedini1Clifford Butcher2Michael J. Worswick3Department of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, CanadaDepartment of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, CanadaDepartment of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, CanadaDepartment of Mechanical and Mechatronics Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, CanadaEmerging grades of press-hardening steels such as Ductibor<sup>®</sup> 1000-AS are now commercially available for use within tailor-welded blanks (TWBs) to enhance ductility and energy absorption in hot-stamped automotive structural components. This study examines the constitutive (hardening) response and fracture limits of Ductibor<sup>®</sup> 1000-AS as functions of the as-quenched microstructure after hot stamping. Three different microstructures consisting of bainite and martensite were obtained by hot stamping with die temperatures of 25 °C, 350 °C, and 450 °C. Mechanical characterization was performed to determine the hardening curves and plane-stress fracture <i>loci</i> for the different quench conditions (cooling rates). Uniaxial-tension and shear tests were conducted to experimentally capture the hardening response to large strain levels. Shear, conical hole-expansion, plane-strain notch tension, and Nakazima tests were carried out to evaluate the stress-state dependence of fracture. A mean-field homogenization (MFH) scheme was applied to model the constitutive and fracture behavior of the mixed-phase microstructures. A dislocation-based hardening model was adopted for the individual phases, which accounts for material chemistry, inter-phase carbon partitioning, and dislocation evolution. The per-phase fracture modelling was executed using a phenomenological damage index based upon the stress state within each phase. The results revealed that the 25 °C hot-stamped material condition with a fully martensite microstructure exhibited the highest level of strength and the lowest degree of ductility. As bainite was formed in the final microstructure by quenching at higher die temperatures, the strength decreased, while the ductility increased. The predicted constitutive and fracture responses in the hot-stamped microstructures were in line with the measured data. Accordingly, the established numerical strategy was extended to predict the mechanical behavior of Ductibor<sup>®</sup> 1000-AS for a broad range of intermediate as-quenched microstructures.https://www.mdpi.com/2075-4701/12/10/1770steeldie quenchinghardeningdamagemicrostructure-based model |
| spellingShingle | Pedram Samadian Armin Abedini Clifford Butcher Michael J. Worswick Microstructure-Based Modelling of Flow and Fracture Behavior of Tailored Microstructures of Ductibor<sup>®</sup> 1000-AS Steel Metals steel die quenching hardening damage microstructure-based model |
| title | Microstructure-Based Modelling of Flow and Fracture Behavior of Tailored Microstructures of Ductibor<sup>®</sup> 1000-AS Steel |
| title_full | Microstructure-Based Modelling of Flow and Fracture Behavior of Tailored Microstructures of Ductibor<sup>®</sup> 1000-AS Steel |
| title_fullStr | Microstructure-Based Modelling of Flow and Fracture Behavior of Tailored Microstructures of Ductibor<sup>®</sup> 1000-AS Steel |
| title_full_unstemmed | Microstructure-Based Modelling of Flow and Fracture Behavior of Tailored Microstructures of Ductibor<sup>®</sup> 1000-AS Steel |
| title_short | Microstructure-Based Modelling of Flow and Fracture Behavior of Tailored Microstructures of Ductibor<sup>®</sup> 1000-AS Steel |
| title_sort | microstructure based modelling of flow and fracture behavior of tailored microstructures of ductibor sup r sup 1000 as steel |
| topic | steel die quenching hardening damage microstructure-based model |
| url | https://www.mdpi.com/2075-4701/12/10/1770 |
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