Microstructure and mechanical properties of intercritically annealed Al-contain medium Mn steel
SHAO Cheng-wei1, WANG Jun-tao1, ZHAO Xiao-li2, HUI Wei-jun2
1. Testing and Damage Evaluation Center, China Aero-Polytechnology Establishment, Beijing 100028, China;
2. School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China
Abstract：In order to investigate the effect of intercritical annealing temperature on the microstructure and mechanical properties of a newly designed cold-rolled aluminum-containing medium Mn steel (0.2C-0.6Si-5Mn-1.2Al)(mass percent,%),the microstructure was characterized by scanning electron microscopy (SEM) and X-ray diffraction(XRD). The mechanical properties were tested by uniaxial tensile test. The results show that an excellent combination of ultimate tensile strength (UTS) of 1 276 MPa,total elongation (TEL) of 51.8% and UTS×TEL of 66.1 GPa·% could be obtained after annealing at 670 ℃ for 10 min. The inverted austenite of the cold-rolled steel gradually coarsenes and transforms into martensite,and the mechanical stability gradually decreased with increasing intercritical annealing temperature. The mechanical stability of inverted austenite is mainly affected by the content of C in retained austenite and the grain size,while the content of Mn in the retained austenite has little effect on it.
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