|Influence of cold forging and annealing on microstructure and mechanical properties of a high-Mn TWIP steel|
KUSAKIN, P., KALINENKO, A., TSUZAKI, K., BELYAKOV, A., KAIBYSHEV, R.
vol. 55 (2017), no. 3, pp. 161 - 167
The influence of cold biaxial forging and annealing on the microstructure evolution and mechanical properties of Fe-18Mn-0.6C-0.1N TWIP steel was investigated. The microstructure after thermomechanical treatment was examined by means of scanning electron microscopy (SEM) with electron back-scattered diffraction (EBSD) analyzer and transmission electron microscopy (TEM). The microstructure containing a high density of deformation twins was evolved by cold forging. Then, the deformation microstructure was recovered or partially recrystallized during subsequent annealing for 1 h at 673 or 873 K, respectively. The cold biaxial forging followed by partial recrystallization resulted in a very attractive combination of mechanical properties. The yield strength and the ultimate tensile strength of the steel after cold biaxial forging were 1320 and 1540 MPa, respectively, with elongation of 6 %. On the other hand, the yield and ultimate tensile strength of 770 and 1110 MPa, respectively, and elongation about 40 % were obtained after partial recrystallization. The as-forged and recovery annealed samples showed fatigue limit of 600 and 550 MPa, respectively, and the sample after partial recrystallization showed slightly lower fatigue limit of 500 MPa.
TWIP-steel, deformation twinning, microstructure, mechanical properties, fatigue
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