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采用膨胀仪测定了一种1800 MPa级冷轧热成形钢的相变点;通过OM、SEM、EBSD等方法检测了其经热轧和热成形后的显微组织,采用CCT-AY-Ⅱ型钢板连续退火机对其进行热处理,测量了其力学性能。结果表明:热轧后实验钢的组织为珠光体和铁素体,热成形后的组织为马氏体和极少量奥氏体。冷轧热成形钢在850℃保温淬火后其综合力学性能最好,抗拉强度最高达到1845 MPa,屈服强度也达到了1033 MPa,伸长率达到了7.4%;由EBSD分析可知,850℃保温后实验钢具有细小的原始奥氏体晶粒和马氏体组织及较高密度的小角度晶界,这是其保持较高的强度和伸长率的原因。
The phase transition point of a 1800 MPa grade cold-rolled thermoformed steel was measured by dilatometer. The microstructure of the cold-formed thermoformed steel was investigated by OM, SEM and EBSD. The microstructure of the cold-rolled thermoformed steel was characterized by CCT-AY-Ⅱ Steel continuous annealing machine for heat treatment, measuring its mechanical properties. The results show that the microstructure of hot rolled steel is pearlite and ferrite. The microstructure after hot forming is martensite and very small amount of austenite. Cold-rolled thermoformed steel quenched at 850 ℃ after quenching its best mechanical properties, the highest tensile strength reached 1845 MPa, yield strength also reached 1033 MPa, elongation reached 7.4%; from EBSD analysis shows that 850 ℃ insulation The post-experimental steel has fine primary austenite grain and martensite and a higher density of small angle grain boundaries, which is why it maintains high strength and elongation.