Microstructure Evolution and Mechanical Properties of 67GPa•% Grade Medium Manganese Steel

Abstract:

In this study, a new Fe-6Mn-4Al-0.4C high strength medium manganese hot rolled steel sheet was designed. The influence mechanism of the intercritical annealing (IA) temperature on microstructure evolution and mechanical properties of experimental steel were studied by SEM and XRD. The experimental steel was held for 30 minutes at 640°C, 680°C, 720°C, 760°C, 800°C, respectively. When the annealing temperature was 640°C, cementite particles precipitated between the austenite and ferrite phase boundary. As the annealing temperature increased, the cementite gradually dissolved and disappeared, the fraction of lamellar austenite increased significantly. When the annealing temperature is 800°C, the coarse equiaxed austenite and ferrite appeared. The yield strength (YS) decreased, the product of strength and elongation (PSE) and total elongation (TE) both increased first and then decreased, while the ultimate tensile strength (UTS) showed the opposite trend. The experimental steel exhibited excellent comprehensive mechanical properties after held at 760°C for 30 min. The UTS was 870 MPa, the YS was 703 MPa, and the TE was 77 %, the PSE was 67 GPa·%.

• Periodical: Materials Science Forum (Volume 1035)
• Pages: 404-409
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1035.404
• Online since: June 2021
• Authors: Zhe Rui Zhang, Ren Bo Song*, Nai Peng Zhou, Wei Feng Huo
• Keywords: Austenite Stability, Fe-Mn-Al-C, Intercritical Annealing, Tensile Properties

References

[1] Cai Z.H, Ding H, Misra R.D.K, et al. Austenite stability and deformation behavior in a cold-rolled transformation-induced plasticity steel with medium manganese content[J]. Acta Mater. 84 (2015) 229-236.

DOI: 10.1016/j.actamat.2014.10.052

[2] Suh D.W, Kim S.J. Medium Mn transformation-induced plasticity steels: Recent progress and challenges[J]. Scripta Mater. 126 (2017) 63-67.

DOI: 10.1016/j.scriptamat.2016.07.013

[3] Steineder K, Krizan D, Schneider R, et al. On the microstructural characteristics influencing the yielding behavior of ultra-fine grained medium-Mn steels[J]. Acta Mater. 139 (2017) 39-50.

DOI: 10.1016/j.actamat.2017.07.056

[4] Shi J, Sun X, Wang M, et al. Enhanced work-hardening behavior and mechanical properties in ultrafine-grained steels with large-fractioned metastable austenite[J]. Scripta Mater. 63 (2010) 815-818.

DOI: 10.1016/j.scriptamat.2010.06.023

[5] S.-J. Park, B. Hwang, K.H. Lee, et al. Microstructure and tensile behavior of duplex low-density steel containing 5mass% aluminum[J]. Scripta Mater. 68 (2013) 365-369.

DOI: 10.1016/j.scriptamat.2012.09.030

[6] Sohn S S, Lee B J, Lee S, et al. Effect of annealing temperature on microstructural modification and tensile properties 0.35 C–3.5 Mn–5.8 Al lightweight steel[J]. Acta Mater. 61 (2013) 5050-5066.

DOI: 10.1016/j.actamat.2013.04.038

[7] Cai Z H, Ding H, Misra R D K, et al. Mechanistic contribution of the interplay between microstructure and plastic deformation in hot-rolled Fe–11Mn–2/4Al–0.2C steel[J]. Mater. Sci. Eng. A, 652 (2016) 205-211.

DOI: 10.1016/j.msea.2015.11.084

[8] Zhou N, Song R, Li X, et al. Dependence of austenite stability and deformation behavior on tempering time in an ultrahigh strength medium Mn TRIP steel[J]. Mater. Sci. Eng. A 738 (2018). 153-162.

DOI: 10.1016/j.msea.2018.09.098

[9] Li J, Song R, Li X, et al. Microstructural Evolution and Tensile Properties of 70GPa·% Grade Strong and Ductile Hot-rolled 6Mn Steel Treated by Intercritical Annealing[J]. Mater. Sci. Eng. A 745 (2019) 212-220.

DOI: 10.1016/j.msea.2018.12.110

[10] Li Z.C, Ding H, et al. Mechanical properties and austenite stability in hot-rolled 0.2C–1.6/3.2Al–6Mn–Fe TRIP steel[J]. Mater. Sci. Eng. A 639 (2015) 559-566.

DOI: 10.1016/j.msea.2015.05.061

[11] Li X, Song R, Zhou N, et al. Microstructure and tensile behavior of Fe-8Mn-6Al-0.2C low density steel[J]. Mater. Sci. Eng. A. 709 (2017) 97-104.

DOI: 10.1016/j.msea.2017.10.039

[12] Zhang S, Findley K O. Quantitative assessment of the effects of microstructure on the stability of retained austenite in TRIP steels[J]. Acta Mater. 61 (2013) 1895-1903.

DOI: 10.1016/j.actamat.2012.12.010

[13] Kim J K, Kim J H, Suh D W. Partially-recrystallized ferrite grains and multiple plasticity enhancing mechanisms in a medium Mn steel[J]. Mater. Charact 155 (2019) 109812.

DOI: 10.1016/j.matchar.2019.109812

[14] Zhou S, Zhang K, Wang Y, et al. High strength-elongation product of Nb-microalloyed low-carbon steel by a novel quenching–partitioning–tempering process[J]. Mater. Sci. Eng. A. 528 (2011) 8006-8012.

DOI: 10.1016/j.msea.2011.07.008