Details
| Original language | English |
|---|---|
| Pages (from-to) | 3022-3033 |
| Number of pages | 12 |
| Journal | Acta materialia |
| Volume | 60 |
| Issue number | 6-7 |
| Publication status | Published - 7 Mar 2012 |
| Externally published | Yes |
Abstract
The multiphase constitution of a transformation-induced plasticity (TRIP)-assisted steel with a nominal composition of Fe-1.5Mn-1.5Si-0.3C (wt.%) was designed, utilizing a combination of computational methods and experimental validation, in order to achieve significant improvements in both strength and ductility. In this study, it was hypothesized that a microstructure with maximized ferrite and retained austenite volume fractions would optimize the strain hardening and ductility of multiphase TRIP-assisted steels. Computational thermodynamics and kinetics calculations were used to develop a predictive methodology to determine the processing parameters in order to reach maximum possible ferrite and retained austenite fractions during conventional two-stage heat treatment, i.e. intercritical annealing followed by bainitic isothermal transformation. Experiments were utilized to validate and refine the design methodology. Equal channel angular pressing was employed at a high temperature (950 °C) on the as-cast ingots as the initial processing step in order to form a homogenized microstructure with uniform grain/phase size. Using the predicted heat treatment parameters, a multiphase microstructure including ferrite, bainite, martensite and retained austenite was successfully obtained. The resulting material demonstrated a significant improvement in the true ultimate tensile strength (∼1300 MPa) with good uniform elongation (∼23%), as compared to conventional TRIP steels. This provided a mechanical property combination that has not been exhibited before by low-alloy first-generation high-strength steels. The developed computational framework for the selection of heat treatment parameters can also be utilized for other TRIP-assisted steels and help design new microstructures for advanced high-strength steels, minimizing the need for cumbersome experimental optimization.
Keywords
- Computational thermodynamics, Equal channel angular pressing (ECAP), Mechanical behavior, Phase transformations, TRIP-assisted steels
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Ceramics and Composites
- Materials Science(all)
- Polymers and Plastics
- Materials Science(all)
- Metals and Alloys
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In: Acta materialia, Vol. 60, No. 6-7, 07.03.2012, p. 3022-3033.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Multi-phase microstructure design of a low-alloy TRIP-assisted steel through a combined computational and experimental methodology
AU - Zhu, R.
AU - Li, S.
AU - Karaman, I.
AU - Arroyave, R.
AU - Niendorf, T.
AU - Maier, H. J.
N1 - Funding information: This study is funded by the US National Science Foundation, Division of Civil, Mechanical, and Manufacturing Innovation, Materials and Surface Engineering Program , Grant No. 0900187 . The authors would like to thank Dr. Pedro Rivera, University of Cambridge for discussions during the preparation of this manuscript and Dr. Ray Guillemette, Texas A&M University Geology & Geophysics Department for the microprobe analyses.
PY - 2012/3/7
Y1 - 2012/3/7
N2 - The multiphase constitution of a transformation-induced plasticity (TRIP)-assisted steel with a nominal composition of Fe-1.5Mn-1.5Si-0.3C (wt.%) was designed, utilizing a combination of computational methods and experimental validation, in order to achieve significant improvements in both strength and ductility. In this study, it was hypothesized that a microstructure with maximized ferrite and retained austenite volume fractions would optimize the strain hardening and ductility of multiphase TRIP-assisted steels. Computational thermodynamics and kinetics calculations were used to develop a predictive methodology to determine the processing parameters in order to reach maximum possible ferrite and retained austenite fractions during conventional two-stage heat treatment, i.e. intercritical annealing followed by bainitic isothermal transformation. Experiments were utilized to validate and refine the design methodology. Equal channel angular pressing was employed at a high temperature (950 °C) on the as-cast ingots as the initial processing step in order to form a homogenized microstructure with uniform grain/phase size. Using the predicted heat treatment parameters, a multiphase microstructure including ferrite, bainite, martensite and retained austenite was successfully obtained. The resulting material demonstrated a significant improvement in the true ultimate tensile strength (∼1300 MPa) with good uniform elongation (∼23%), as compared to conventional TRIP steels. This provided a mechanical property combination that has not been exhibited before by low-alloy first-generation high-strength steels. The developed computational framework for the selection of heat treatment parameters can also be utilized for other TRIP-assisted steels and help design new microstructures for advanced high-strength steels, minimizing the need for cumbersome experimental optimization.
AB - The multiphase constitution of a transformation-induced plasticity (TRIP)-assisted steel with a nominal composition of Fe-1.5Mn-1.5Si-0.3C (wt.%) was designed, utilizing a combination of computational methods and experimental validation, in order to achieve significant improvements in both strength and ductility. In this study, it was hypothesized that a microstructure with maximized ferrite and retained austenite volume fractions would optimize the strain hardening and ductility of multiphase TRIP-assisted steels. Computational thermodynamics and kinetics calculations were used to develop a predictive methodology to determine the processing parameters in order to reach maximum possible ferrite and retained austenite fractions during conventional two-stage heat treatment, i.e. intercritical annealing followed by bainitic isothermal transformation. Experiments were utilized to validate and refine the design methodology. Equal channel angular pressing was employed at a high temperature (950 °C) on the as-cast ingots as the initial processing step in order to form a homogenized microstructure with uniform grain/phase size. Using the predicted heat treatment parameters, a multiphase microstructure including ferrite, bainite, martensite and retained austenite was successfully obtained. The resulting material demonstrated a significant improvement in the true ultimate tensile strength (∼1300 MPa) with good uniform elongation (∼23%), as compared to conventional TRIP steels. This provided a mechanical property combination that has not been exhibited before by low-alloy first-generation high-strength steels. The developed computational framework for the selection of heat treatment parameters can also be utilized for other TRIP-assisted steels and help design new microstructures for advanced high-strength steels, minimizing the need for cumbersome experimental optimization.
KW - Computational thermodynamics
KW - Equal channel angular pressing (ECAP)
KW - Mechanical behavior
KW - Phase transformations
KW - TRIP-assisted steels
UR - http://www.scopus.com/inward/record.url?scp=84862810222&partnerID=8YFLogxK
U2 - 10.1016/j.actamat.2012.02.007
DO - 10.1016/j.actamat.2012.02.007
M3 - Article
AN - SCOPUS:84862810222
VL - 60
SP - 3022
EP - 3033
JO - Acta materialia
JF - Acta materialia
SN - 1359-6454
IS - 6-7
ER -