Recently, medium-Mn steels have attracted attention for high-strength automotive components. However, because they exhibit martensitic microstructure at room temperature, low cold roll-ability is concerned so that annealing or tempering is often performed before cold rolling. Therefore, we investigated whether cold roll-ability can be improved by adjusting coiling condition in the hot rolling process. For comparison, some specimens were water-quenched or air-cooled after hot rolling. While the water-quenched specimen revealed cracks at ∼30% cold reduction, air-cooled and coiling-simulated specimens at high reductions above ∼68%. This is because the latter had lower and wider ranged hardness values compared to the former due to partial auto-tempering occurring after coiling. The higher coiling temperature caused higher cold roll-ability probably due to the active recovery of austenite.
This paper is part of a Thematic Issue on Medium Manganese Steels.
ZhongN, WangXD, WangL, Enhancement of the mechanical properties of a Nb-microalloyed advanced high-strength steel treated by quenching–partitioning–tempering process. Mater Sci Eng A. 2009;506:111–116. doi: 10.1016/j.msea.2008.11.014
2.
EdmondsDV, HeK, RizzoFC, Quenching and partitioning martensite–A novel steel heat treatment. Mater Sci Eng A. 2006;438–440:25–34. doi: 10.1016/j.msea.2006.02.133
3.
SeoC-H, KwonKH, ChoiK, Deformation behavior of ferrite–austenite duplex lightweight Fe–Mn–Al–C steel. Scripta Mater. 2012;66:519–522. doi: 10.1016/j.scriptamat.2011.12.026
4.
HanSY, ShinSY, LeeH-J, Effects of annealing temperature on microstructure and tensile properties in ferritic lightweight steels. Metall Mater Trans A. 2012;43:843–853. doi: 10.1007/s11661-011-0942-2
5.
DingR, DaiZ, HuangM, Effect of pre-existed austenite on austenite reversion and mechanical behavior of an Fe-0.2C-8Mn-2Al medium Mn steel. Acta Mater. 2018;147:59–69. doi: 10.1016/j.actamat.2018.01.009
6.
YangF, LuoH, HuC, Effects of intercritical annealing process on microstructures and tensile properties of cold-rolled 7Mn steel. Mater Sci Eng A. 2017;685:115–122. doi: 10.1016/j.msea.2016.12.119
7.
SuhD-W, KimS-J.Medium Mn transformation-induced plasticity steels: recent progress and challenges. Scripta Mater. 2017;126:63–67. doi: 10.1016/j.scriptamat.2016.07.013
8.
MaY.Medium-manganese steels processed by austenite-reverted-transformation annealing for automotive applications. Mater Sci Technol. 2017;33:1713–1727. doi: 10.1080/02670836.2017.1312208
9.
HuB, LuoH, YangF, Recent progress in medium-Mn steels made with new designing strategies, a review. J Mater Sci Technol. 2017;33:1457–1464. doi: 10.1016/j.jmst.2017.06.017
10.
HanJ, da SilvaAK, PongeD, The effects of prior austenite grain boundaries and microstructural morphology on the impact toughness of intercritically annealed medium Mn steel. Acta Mater. 2017;122:199–206. doi: 10.1016/j.actamat.2016.09.048
11.
ArlazarovA, GounéM, BouazizO, Critical factors governing the thermal stability of austenite in an ultra-fined grained medium-Mn steel. Philos Mag Lett. 2017;97:125–131. doi: 10.1080/09500839.2017.1290293
12.
HanJ, NamJ-H, LeeY-K.The mechanism of hydrogen embrittlement in intercritically annealed medium Mn TRIP steel. Acta Mater. 2016;113:1–10. doi: 10.1016/j.actamat.2016.04.038
13.
CaiMH, ZhuWJ, StanfordN, Dependence of deformation behavior on grain size and strain rate in an ultrahigh strength-ductile Mn-based TRIP alloy. Mater Sci Eng A. 2016;653:35–42. doi: 10.1016/j.msea.2015.11.103
14.
LuoH, DongH, HuangM.Effect of intercritical annealing on the Lüders strains of medium Mn transformation-induced plasticity steels. Mater Des. 2015;83:42–48. doi: 10.1016/j.matdes.2015.05.085
15.
LeeY-K, HanJ.Current opinion in medium manganese steel. Mater Sci Tech. 2015;31:843–856. doi: 10.1179/1743284714Y.0000000722
16.
HanJ, LeeY-K.The effects of the heating rate on the reverse transformation mechanism and the phase stability of reverted austenite in medium Mn steels. Acta Mater. 2014;67:354–361. doi: 10.1016/j.actamat.2013.12.038
17.
HanJ, LeeSJ, JungJG, The effects of the initial martensite microstructure on the microstructure and tensile properties of intercritically annealed Fe-9Mn-0.05C steel. Acta Mater. 2014;78:369–377. doi: 10.1016/j.actamat.2014.07.005
18.
SuhDW, RyuJH, JooMS, Medium-alloy manganese-rich transformation-induced plasticity steels. Metall Mater Trans A. 2013;44:286–293. doi: 10.1007/s11661-012-1402-3
19.
HanamuraT, TorizukaS, TamuraS, Effect of austenite grain size on transformation behavior, microstructure and mechanical properties of 0.1C-5Mn martensitic steel. ISIJ Int. 2013;53:2218–2225. doi: 10.2355/isijinternational.53.2218
20.
AydinH, EssadiqiE, JungIH, Effect of intercritical heat treatment on the microstructure and mechanical properties of medium Mn steels. ISIJ Int. 2013;53:1871–1880. doi: 10.2355/isijinternational.53.1871
21.
XuHF, ZhaoJ, CaoWQ, Heat treatment effects on the microstructure and mechanical properties of a medium manganese steel (0.2C-5Mn). Mater Sci Eng A. 2012;532:435–442. doi: 10.1016/j.msea.2011.11.009
22.
LeeSJ, LeeS, De CoomanBC.Mn partitioning during the intercritical annealing of ultrafine-grained 6% Mn transformation-induced plasticity steel. Scripta Mater. 2011;64:649–652. doi: 10.1016/j.scriptamat.2010.12.012
23.
GibbsPJ, De MoorE, MerwinMJ, Austenite stability effects on tensile behavior of manganese-enriched-austenite transformation-induced plasticity steel. Metall Mater Trans A. 2011;42:3691–3702. doi: 10.1007/s11661-011-0687-y
24.
CaoWQ, WangC, ShiJ, Microstructure and mechanical properties of Fe-0.2C-5Mn steel processed by ART-annealing. Mater Sci Eng A. 2011;528:6661–6666. doi: 10.1016/j.msea.2011.05.039
25.
ShiJ, SunX, WangM, Enhanced work-hardening behavior and mechanical properties in ultrafine-grained steels with large-fractioned metastable austenite. Scripta Mater. 2010;63:815–818. doi: 10.1016/j.scriptamat.2010.06.023
26.
MillerRL.Ultrafine-grained microstructures and mechanical properties of alloy steels. Metall Trans. 1972;3:905–912. doi: 10.1007/BF02647665
27.
SunB, VanderesseN, FazeliF, Discontinuous strain-induced martensite transformation related to the Portevin-Le Chatelier effect in a medium manganese steel. Scripta Mater. 2017;133:9–13. doi: 10.1016/j.scriptamat.2017.01.022
28.
KangS, SpeerJG, KrizanD, Prediction of tensile properties of intercritically annealed Al-containing 0.19C–4.5Mn (wt%) TRIP steels. Mater Des. 2016;97:138–146. doi: 10.1016/j.matdes.2016.02.058
29.
MatsudaH, MizunoR, FunakawaY, Effects of auto-tempering behaviour of martensite on mechanical properties of ultra high strength steel sheets. J Alloys Compd. 2013;577:S661–S667. doi: 10.1016/j.jallcom.2012.04.108
30.
LiCN, YuanG, JiFQ, Effects of auto-tempering on microstructure and mechanical properties in hot rolled plain C-Mn dual phase steels. Mater Sci Eng A. 2016;665:98–107. doi: 10.1016/j.msea.2016.04.038
31.
OhlundCEIC, SchlangenE, Erik OffermanS.The kinetics of softening and microstructure evolution of martensite in Fe–C–Mn steel during tempering at 300°C. Mater Sci Eng A. 2013;560:351–357. doi: 10.1016/j.msea.2012.09.078
32.
DmitrievaO, PongeD, IndenG, Chemical gradients across phase boundaries between martensite and austenite in steel studied by atom probe tomography and simulation. Acta Mater. 2011;59:364–374. doi: 10.1016/j.actamat.2010.09.042
33.
KuzminaM, PongeD, RaabeD.Grain boundary segregation engineering and austenite reversion turn embrittlement into toughness: example of a 9 wt.% medium Mn steel. Acta Mater. 2015;86:182–192. doi: 10.1016/j.actamat.2014.12.021
