This paper introduces a new alloying concept for low-density steels. Based on model calculations, samples-or "heats"-with 0.7 wt% C, 1.45 wt% Si, 2 wt% Cr, 0.5 wt% Ni, and an aluminium content varying from 5 to 7 wt% are prepared. The alloys are designed to obtain steel with reduced density and increased corrosion resistance suitable for products subjected to high dynamic stress during operation. Their density is in the range from 7.2 g cm-3 to 6.96 g cm-3. Basic thermophysical measurements are carried out on all the heats to determine the critical points of each phase transformation in the solid state, supported by metallographic analysis on SEM and LM or the EDS analysis of each phase. It is observed that even at very high austenitisation temperatures of 1100 °C, it is not possible to change the two-phase structure of ferrite and austenite. A substantial part of the austenite is transformed into martensite during cooling at 50 °C s-1. The carbide kappa phase is segregated at lower cooling rates (around 2.5 °C s-1).

COMTES FHT a s Prumyslova 995 334 41 Dobrany Czech Republic

Regional Technological Institute University of West Bohemia Univerzitni 8 301 00 Plzen Czech Republic

Zobrazit více v PubMed

Suh D.W., Kim N.J. Low-Density Steels. Scr. Mater. 2013;68:337–338. doi: 10.1016/j.scriptamat.2012.11.037. DOI

Frommeyer G., Brüx U. Microstructures and Mechanical Properties of High-Strength Fe-Mn-Al-C Light-Weight TRIPLEX Steels. Steel Res. Int. 2006;77:627–633. doi: 10.1002/srin.200606440. DOI

Kim H., Suh D.W., Kim N.J. Fe-Al-Mn-C Lightweight Structural Alloys: A Review on the Microstructures and Mechanical Properties. Sci. Technol. Adv. Mater. 2013;14 doi: 10.1088/1468-6996/14/1/014205. PubMed DOI PMC

Pramanik S., Koppoju S., Anupama A.V., Sahoo B., Suwas S. Strengthening Mechanisms in Fe-Al Based Ferritic Low-Density Steels. Mater. Sci. Eng. A. 2018;712:574–584. doi: 10.1016/j.msea.2017.10.056. DOI

Rawat P., Prakash U., Prasad V.V.S. Phase Transformation and Hot Working Studies on High-Al Fe-Al-Mn-C Ferritic Low-Density Steels. J. Mater. Eng. Perform. 2021;30:6297–6308. doi: 10.1007/s11665-021-05857-3. DOI

Pramanik S., Suwas S. Low-Density Steels: The Effect of Al Addition on Microstructure and Properties. Jom. 2014;66:1868–1876. doi: 10.1007/s11837-014-1129-2. DOI

Man T., Wang W., Zhou Y., Liu T., Lu H., Zhao X., Zhang M., Dong H. Effect of Cooling Rate on the Precipitation Behavior of κ-Carbide in Fe-32Mn-11Al-0.9C Low Density Steel. Mater. Lett. 2022;314:131778. doi: 10.1016/j.matlet.2022.131778. DOI

Kaltzakorta I., Gutierrez T., Elvira R., Jimbert P., Guraya T. Evolution of Microstructure during Isothermal Treatments of a Duplex-Austenitic 0.66C11.4Mn.9.9Al Low-Density Forging Steel and Effect on the Mechanical Properties. Metals. 2021;11:214. doi: 10.3390/met11020214. DOI

Chang K.M., Chao C.G., Liu T.F. Excellent Combination of Strength and Ductility in an Fe-9Al-28Mn-1.8C Alloy. Scr. Mater. 2010;63:162–165. doi: 10.1016/j.scriptamat.2010.03.038. DOI

Wei L.L., Gao G.H., Kim J., Misra R.D.K., Yang C.G., Jin X.J. Ultrahigh Strength-High Ductility 1 GPa Low Density Austenitic Steel with Ordered Precipitation Strengthening Phase and Dynamic Slip Band Refinement. Mater. Sci. Eng. A. 2022;838:142829. doi: 10.1016/j.msea.2022.142829. DOI

Raabe D., Springer H., Gutierrez-Urrutia I., Roters F., Bausch M., Seol J.B., Koyama M., Choi P.P., Tsuzaki K. Alloy Design, Combinatorial Synthesis, and Microstructure–Property Relations for Low-Density Fe-Mn-Al-C Austenitic Steels. Jom. 2014;66:1845–1856. doi: 10.1007/s11837-014-1032-x. DOI

Lee H.J., Sohn S.S., Lee S., Kwak J.H., Lee B.J. Thermodynamic Analysis of the Effect of C, Mn and Al on Microstructural Evolution of Lightweight Steels. Scr. Mater. 2013;68:339–342. doi: 10.1016/j.scriptamat.2012.10.032. DOI

Eskandari M., Zarei-Hanzaki A., Kamali A.R., Mohtadi-Bonab M.A., Szpunar J.A. Strain Hardening During Hot Compression Through Planar Dislocation and Twin-Like Structure in a Low-Density High-Mn Steel. J. Mater. Eng. Perform. 2014;23:3567–3576. doi: 10.1007/s11665-014-1168-4. DOI

Wan P., Kang T., Li F., Gao P., Zhang L., Zhao Z. Dynamic Recrystallization Behavior and Microstructure Evolution of Low-Density High-Strength Fe–Mn–Al–C Steel. J. Mater. Res. Technol. 2021;15:1059–1068. doi: 10.1016/j.jmrt.2021.08.079. DOI

Gutierrez-Urrutia I. Low Density Fe-Mn-Al-C Steels: Phase Structures, Mechanisms and Properties. ISIJ Int. 2021;61:16–25. doi: 10.2355/isijinternational.ISIJINT-2020-467. DOI

Chen S., Rana R., Haldar A., Ray R.K. Current State of Fe-Mn-Al-C Low Density Steels. Prog. Mater. Sci. 2017;89:345–391. doi: 10.1016/j.pmatsci.2017.05.002. DOI

Hallstedt B., Khvan A.V., Lindahl B.B., Selleby M., Liu S. PrecHiMn-4—A Thermodynamic Database for High-Mn Steels. Calphad Comput. Coupling Phase Diagr. Thermochem. 2017;56:49–57. doi: 10.1016/j.calphad.2016.11.006. DOI

Sohn S.S., Choi K., Kwak J.H., Kim N.J., Lee S. Novel Ferrite-Austenite Duplex Lightweight Steel with 77% Ductility by Transformation Induced Plasticity and Twinning Induced Plasticity Mechanisms. Acta Mater. 2014;78:181–189. doi: 10.1016/j.actamat.2014.06.059. DOI

Kim S.H., Kim H., Kim N.J. Brittle Intermetallic Compound Makes Ultrastrong Low-Density Steel with Large Ductility. Nature. 2015;518:77–79. doi: 10.1038/nature14144. PubMed DOI

JMatPro . Materials Property Simulation Package Public Release. Sente Software Ltd.; Guildford, UK: 2019.

Ashby M.F. Materials Selection in Mechanical Design. 2nd ed. Volume 3. Elsevier; Amsterdam, The Netherlands: 1992. p. 665.

Becker P. Low Density Steels for Light Springs. Wuppertal, Germany: 2019.

Mechanical Properties of High Carbon Low-Density Steels