OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 2 2025 60 % or higher reductions, the material from the rod center exhibits a decrease in uniform elongation to 0.2-0.3 % and a relative elongation of less than 10 % (Table). The material of the edge of the rod demonstrates a uniform elongation at the level of 1.2-1.7 %, and a relative elongation of about 14-17 %. Conclusion Based on the results of the study of the evolution of the microstructure, texture and mechanical properties of the lightweight austenitic steel Fe-21Mn-6Al-1C after various cold radial forging (CRF) modes, the following conclusions can be drawn: – During CRF, the following stages of the microstructure formation are observed: low degrees of deformation (ε up to 20 %) – formation of deformation microbands of various systems in the center and parallel deformation microbands at the edge of the rod; medium degrees of deformation (ε = 40-60 %) – formation of single mechanical twins of various systems in the center and parallel packets of twins at the edge; high degrees of deformation (ε = 80 %) – twinning according to various systems in the center and formation of a fragmented microstructure at the edge. – With an increase in the degree of CRF, pronounced texture gradients are formed in the rod. The twocomponent axial texture <111>// rod axis (RA) and <100>//RA develops in the center of the rod, which is weakened towards the edge. Meanwhile, the pronounced shear texture B/B ̅is found at the edge of the rod after 40 % CRF and higher. – 20 % CRF causes an increase in microhardness of the rod edge to a greater extent compared to the center. Subsequent CRF is accompanied by a further increase in the overall level of microhardness. After a deformation of 60%, a pronounced peak of microhardness appears in the core of the rod. After 80 % CRF, this peak reaches 600 HV0.2. – After 20 % CRF, the material of the rod center exhibits higher strength and lower ductility compared to the material of the rod edge. With further CRF, the strength becomes higher at the center of the rod, whereas the ductility is higher at the edge. Thus, after 80 % CRF, elongation to failure is δ ≈ 6 % at the center and δ ≈ 15 % at the edge. The strength properties of the central part of the rod (σu = ,2062 MPa; σ0.2 = 2,062 MPa) exceed these characteristics of the edge (σu = 1,741 MPa; σ0.2 = 1,626 MPa) by 20-30 %. References 1. Chen S., Rana R., Haldar A., Ray R.K. Current state of Fe-Mn-Al-C low density steels. Progress in Materials Science, 2017, vol. 89, pp. 345–391. DOI: 10.1016/j.pmatsci.2017.05.002. 2. 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, vol. 66, pp. 1845–1856. DOI: 10.1007/s11837-014-1032-x. 3. Ding H., Liu D., Cai M., Zhang Y. Austenite-based Fe-Mn-Al-C lightweight steels: research and prospective. Metals, 2022, vol. 12 (10), p. 1572. DOI: 10.3390/met12101572. 4. Kim H., Suh D., Kim N.J., Kim H., Suh D., Kim N.J. Fe–Al–Mn–C lightweight structural alloys: a review on the microstructures and mechanical properties. Science and Technology of Advanced Materials, 2013, vol. 14 (1), p. 014205. DOI: 10.1088/1468-6996/14/1/014205. 5. Yoo J.D., Hwang S.W., Park K.T. Origin of extended tensile ductility of a Fe-28Mn-10Al-1C steel. Metallurgical and Materials Transactions: A, 2009, vol. 40 (7), pp. 1520–1523. DOI: 10.1007/s11661-009-9862-9. 6. Moon J., Park S.J., Jang J.H., Lee T.H., Lee C.H., Hong H.U., Han H.N., Lee J., Lee B.H., Lee C. Investigations of the microstructure evolution and tensile deformation behavior of austenitic Fe-Mn-Al-C lightweight steels and the effect of Mo addition. Acta Materialia, 2018, vol. 147, pp. 226–235. DOI: 10.1016/j.actamat.2018.01.051. 7. Chen P., Zhang F., Zhang Q.C., Du J.H., Shi F., Li X.W. Precipitation behavior of κ-carbides and its relationship with mechanical properties of Fe–Mn–Al–C lightweight austenitic steel. Journal of Materials Research and Technology, 2023, vol. 25 (12), pp. 3780–3788. DOI: 10.1016/j.jmrt.2023.06.212. 8. Harwarth M., Chen G., Rahimi R., Biermann H., Zargaran A., Duffy M., Zupan M., Mola J. Aluminumalloyed lightweight stainless steels strengthened by B2-(Ni,Fe)Al precipitates. Materials & Design, 2021, vol. 206, p. 109813. DOI: 10.1016/j.matdes.2021.109813.
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