Austenite Formation and Cementite Dissolution During Intercritical Annealing of a Medium-Manganese Steel from a Martensitic Condition

14 Pages Posted: 14 Apr 2021 Last revised: 3 Jun 2021

See all articles by John Mueller

John Mueller

affiliation not provided to SSRN

xiao hu

affiliation not provided to SSRN

Xiangge Sun

affiliation not provided to SSRN

Yan Ren

Beijing Genomics Institute (BGI); Beijing Genomics Institute (BGI) - China National Genebank

Jin Kyung Choi

University of Maryland - Robert H. Smith School of Business

Carol E. Barker

Support to the Safe Motherhood Programme

John G. Speer

Colorado School of Mines - Department of Metallurgical and Materials Engineering

D. K. Matlock

affiliation not provided to SSRN

E. De Moor

affiliation not provided to SSRN

Date Written: March 15, 2021

Abstract

In the present study, in situ high-energy X-ray diffraction (HEXRD), dilatometry, and metallography were conducted for the purpose of understanding microstructure evolution during intercritical annealing of a Fe-0.19C-4.39Mn steel from a martensitic initial condition. Three different simulations for austenite growth and solute partitioning during isothermal holding were conducted using the DICTRATMmodule of Thermo-CalcĀ®. The microstructures after intercritical annealing exhibit filmlike retained austenite; however, in situ HEXRD indicates that retained austenite in the initial martensitic microstructure had decomposed upon heating to the isothermal holding temperature, suggesting that film-like austenite may be generated during intercritical annealing via nucleation and growth of new austenite and without necessarily preserving initial retained austenite films in the martensitic microstructure. Metallography and in situ HEXRD also indicate that cementite had formed upon heating but did not readily dissolve during an 1800 s isothermal hold although considerable growth of austenite had occurred during the isothermal hold, suggesting that austenite nucleation and initial growth during intercritical annealing does not solely occur due to carbon partitioning. A simulation incorporating cementite suggests that the increase in austenite fraction during intercritical annealing initially occurs in association with Mn partitioning followed by austenite growth induced by gradual cementite dissolution.

Keywords: in situ high-energy X-ray diffraction, Simulation, Medium-manganese Steel, Austenite, Cementite dissolution

Suggested Citation

Mueller, John and hu, xiao and Sun, Xiangge and Ren, Yan and Choi, Jin Kyung and Barker, Carol E. and Speer, John G. and Matlock, D. K. and Moor, E. De, Austenite Formation and Cementite Dissolution During Intercritical Annealing of a Medium-Manganese Steel from a Martensitic Condition (March 15, 2021). Available at SSRN: https://ssrn.com/abstract=3805221 or http://dx.doi.org/10.2139/ssrn.3805221

John Mueller

affiliation not provided to SSRN

Xiao Hu

affiliation not provided to SSRN

Xiangge Sun

affiliation not provided to SSRN

Yan Ren (Contact Author)

Beijing Genomics Institute (BGI)

Shenzhen, Guangdong 518083
China

Beijing Genomics Institute (BGI) - China National Genebank

Shenzhen
China

Jin Kyung Choi

University of Maryland - Robert H. Smith School of Business ( email )

College Park, MD 20742-1815
United States

Carol E. Barker

Support to the Safe Motherhood Programme ( email )

Kathmandu
Nepal

John G. Speer

Colorado School of Mines - Department of Metallurgical and Materials Engineering

United States

D. K. Matlock

affiliation not provided to SSRN

E. De Moor

affiliation not provided to SSRN

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