Microstructure and mechanical properties of Fe-15Mn-8Al-0.25C low density steel based on FactSage

doi:10.13251/j.issn.0254-6051.2022.07.035

Abstract

Abstract: Solidification and cooling path, phase transformation and precipitates of Fe-(10-20)Mn-(5-10)Al-(0-0.5)C low density steel were simulated by FactSage software. The vertical sections of this system were calculated by using the FSstel database of FactSage software. Based on these vertical sections, the influence of Mn, Al and C on phase transformation and precipitates was analyzed during solidification and a diagram of the phase-transformation path of the Fe-15Mn-8Al-0.25C low density steel was obtained during equilibrium solidification. The results indicate that the equilibrium phases of the Fe-15Mn-8Al-0.25C steel calculated by thermodynamics include liquid, ferrite, austenite and κ-carbide. The full-phase transformation path of the Fe-15Mn-8Al-0.25C steel cooled from 1600 ℃ to 600 ℃ is as follows: liquid→liquid+ferrite→liquid+ferrite+austenite→ferrite+austenite→ferrite+austenite+κ-carbide. The increase of C and Mn content can expand the austenite phase zone of the Fe-15Mn-8Al-0.25C steel, and the increase of Al element can reduce the austenite phase zone. The precipitation temperature of κ-carbide increases with the increase of Al and C content, and Al and C can promote the precipitation of κ-carbide precipitation. The tensile strength of the Fe-15Mn-8Al-0.25C steel aged at 800 ℃ for 3 h is 602 MPa, the yield strength is 520 MPa, the elongation after fracture is 28.6%, the tensile strength aged at 800 ℃ for 5 h is 729 MPa, the yield strength is 685 MPa, and the elongation after fracture is 22.4%. With the increase of aging time, the strength of the tested steel increases and the elongation after fracture decreases. The density of the Fe-15Mn-8Al-0.25C steel is 6.99 g/cm³, which is 10.4% weight lighter than common steel.

Key words: low density steel, κ-carbide, precipitation behavior, phase transformation, solidification mode, phase diagram calculation

CLC Number:

TG142.7

Wang Yinghu. Microstructure and mechanical properties of Fe-15Mn-8Al-0.25C low density steel based on FactSage[J]. Heat Treatment of Metals, 2022, 47(7): 203-210.

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