Microstructures and Properties of Low-Density High Strength-Toughness Fe-18Mn-9.5Al-0.65C Steel

Abstract:

With excellent mechanical properties and low density, Fe-Mn-Al-C steel would be the first choice for automotive lightweight design in future. In this paper, microstructural evolution, mechanical properties and strain hardening behavior of Fe-18Mn-9.5Al-0.65C steel before and after solution treatment were investigated. The experimental steel had (α+γ) duplex phase structure, density of 6.82g/cm³ and high product of strength and ductility. After hot rolling, the steel showed microstructural morphology of austenite matrix and banded ferrite, tensile strength of over 1000MPa and elongation of 25%. During solution treatment, the tensile strength, as well as the yielding strength, decreased with the increase of solution temperature, while the elongation increased first and then decreased sharply for excessively coarsening of grains. After solution treated at 1000°C for 1h, the elongation reached 44%, and product of strength and ductility was 34GPa·%, which was 36% higher than that of the hot-rolled steel. Excellent comprehensive properties are attributed to the multiple-stage strain hardening behavior during tensile deformation, as well as the crush and separation of banded ferrite to form a uniform structure during solution treatment.

• Periodical: Materials Science Forum (Volume 817)
• Pages: 293-298
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.817.293
• Online since: April 2015
• Authors: Lei Feng Zhang*, Ren Bo Song, Chao Zhao, Fu Qiang Yang, Shuai Qin
• Keywords: (α+γ) Duplex Structure, Automotive Steel, Fe-Mn-Al-C, Low-Density High Strength-Toughness Steel, Solution Treatment, Strain Hardening Behavior

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