Mechanism of Cementite Spheroidization from Different Initial Microstructures in Fe-0.65C-2.33Mn Alloy

Abstract:

The spheroidization mechanism from different initial microstructures during spheroidizing heat treatment was studied in Fe-0.68C-2.33Mn alloy. Two types of initial microstructures, i.e. pearlite and martensite, were obtained by varying the cooling rate. The microstructure and property evolution during spheroidizing annealing was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The DICTRA software, assuming local equilibrium conditions, was used to simulate the carburizing process of different initial microstructures through different cooling rate. The results indicate that the spheroidization mechanism of cementite was related to the initial microstructures and the smaller lamellar spacing of pearlite inhibited the coarsening of cementite, resulting in the size of cementite smaller than that of martensite as the initial structure.

• Periodical: Key Engineering Materials (Volume 815)
• Pages: 107-113
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.815.107
• Online since: August 2019
• Authors: Li Ma, Tao Jia, Xiu Hua Gao, Run Ni
• Keywords: Alloy, Cementite, Initial Microstructure, Spheroidization

References

[1] A. Grajcar, R. Kuziak, W. Zalecki, third generation of ahss with increased fraction of retained austenite for the automotive industry, Arch Civ Mech Eng. 12 (2012) 334-341.

DOI: 10.1016/j.acme.2012.06.011

[2] O. Bouaziz, S. Allain, C. P. Scott, P. Cugy, D. Barbier, High manganese austenitic twinning induced plasticity steels: A review of the microstructure properties relationships, Curr Opin Solid St M. 15 (2011) 141-168.

DOI: 10.1016/j.cossms.2011.04.002

[3] S. Lee, B. C. De Cooman, On the selection of the optimal intercritical annealing temperature for medium mn trip steel, Metallurgical and Materials Transactions A. 44 (2013) 5018-5024.

DOI: 10.1007/s11661-013-1860-2

[4] Y. K. Lee, J. Han, Current opinion in medium manganese steel, Materials Science and Technology. 31 (2014) 843-856.

DOI: 10.1179/1743284714y.0000000722

[5] S. Lee, K. Lee, B. C. De Cooman, Observation of the twip + trip plasticity-enhancement mechanism in al-added 6 wt pct medium mn steel, Metallurgical and Materials Transactions A. 46 (2015) 2356-2363.

DOI: 10.1007/s11661-015-2854-z

[6] S. Lee, S.-J. Lee, B. C. De Cooman, Austenite stability of ultrafine-grained transformation-induced plasticity steel with mn partitioning, Scripta Materialia. 65 (2011) 225-228.

DOI: 10.1016/j.scriptamat.2011.04.010

[7] B. V. Rao, U.S. Patent 4,544,422. (1985).

[8] J. Lis, J. Morgiel, A. Lis, The effect of mn partitioning in fe-mn-si alloy investigated with stem-eds techniques, Mater Chem Phys. 81 (2003) 466-468.

DOI: 10.1016/s0254-0584(03)00053-1

[9] Information on http://www.thermocalc.com/products-services/software.