Effect of annealing temperature on microstructure and tensile properties of Fe-Mn-Al-C steel

doi:10.13251/j.issn.0254-6051.2021.04.013

Abstract

Abstract: Effect of annealing temperature on microstructure and properties of Fe-19Mn-2Al-0.6C steel was investigated by means of OM, SEM, TEM and tensile testing. The results show that after annealing, the matrix structure of the tested steel is austenite. Due to the different completeness of recovery and recrystallization, the grain size decreases first and then increases with the increase of annealing temperature. Meanwhile, the amount of annealing twins gradually increases, the ultimate tensile strength of the steel continues to decrease, but the total elongation increases first and then decreases. When a certain external load is applied to the steel, a large amount of deformation twins and dislocations will be generated during the deformation. The tangle and pile-up of high-density dislocation at grain boundaries or twin-boundaries can hinder the further movement of dislocations remarkably. The dynamic Hall-Petch effect generated by the intersecting of primary twins and secondary twins, and the interaction of dislocations and twins, together result in a high work hardening capacity of the tested steel. The optimized annealing temperature for Fe-19Mn-2Al-0.6C steel is about 900 ℃, at which the best comprehensive mechanical properties can be obtained, with the tensile strength, the strength-ductility balance, and the elongation being 947.61 MPa, 49.30 GPa·% and 52.03%, respectively.

Key words: TWIP steel, annealing, twinning, dislocation, tensile properties

CLC Number:

TG156.1

Li Ye, Xia Pengcheng, Xie Kun, Cao Meiqing, Tan Yunliang, Jin Xiaolong. Effect of annealing temperature on microstructure and tensile properties of Fe-Mn-Al-C steel[J]. Heat Treatment of Metals, 2021, 46(4): 77-82.

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