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实验室成功试制C-Si-Mn-Cr-Nb系和C-Si-Mn-Nb系超高强双相钢,利用热膨胀仪研究了铬对超高强双相钢相变规律的影响,利用光学显微镜、SEM以及拉伸试验对双相钢的微观组织和力学性能进行检测。实验结果表明:铬使实验用钢的CCT曲线整体右移,抑制铁素体和珠光体的生成,对铁素体开始转变温度影响不大,升高铁素体的终止转变温度,降低贝氏体转变温度,提高奥氏体的淬透性,在相同的冷速条件下,铬的加入更容易得到铁素体+马氏体的双相组织;合金元素铬显著改善双相钢的显微组织,细化晶粒,双相钢的屈服强度从510 MPa升高到535 MPa,抗拉强度从1 080 MPa升高到1 145 MPa,抗拉强度的增幅高于屈服强度,在抗拉强度提高的同时,伸长率升高。
The laboratory successfully trial-produced C-Si-Mn-Cr-Nb and C-Si-Mn-Nb ultrahigh strength dual phase steel, the use of thermal dilatometer study of the phase transition of super high strength dual phase steel, using optical microscopy , SEM and tensile test on the microstructure and mechanical properties of duplex steel. The experimental results show that chromium makes the overall CCT curve shift to the right and suppresses the formation of ferrite and pearlite, which has little effect on the initial transformation temperature of ferrite, increases the termination temperature of ferrite and decreases the bainite In the same cooling rate condition, the addition of chromium makes it easier to obtain the duplex structure of ferrite + martensite by changing the temperature and increasing the hardenability of austenite. Alloying elemental chromium significantly improves the microstructure of dual phase steel , Grain refinement. The yield strength of dual phase steel increased from 510 MPa to 535 MPa, the tensile strength increased from 1 080 MPa to 1 145 MPa, the increase of tensile strength was higher than that of yield strength, At the same time, the elongation increases.