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为开发具有良好强塑配合的超高强汽车用TRIP钢,设计本试验钢。利用CCT-AY-Ⅱ型连续退火模拟机研究了不同贝氏体区等温温度对试验钢组织和性能的影响。通过DIL 805A型热膨胀仪测定了试验钢的Ac1、Ac3及Ms、Mf点。使用拉伸试验机测定了试验钢的力学性能,通过SEM、EBSD及XRD等技术观察了试验钢的组织及残留奥氏体量。结果表明:试验TRIP钢两相区保温温度为800℃,贝氏体区等温温度为410℃时,综合力学性能最佳,抗拉强度与屈服强度分别达到1114 MPa和485 MPa,伸长率可达20%。试验钢的屈服强度主要由铁素体决定,抗拉强度和伸长率则主要与贝氏体、残留奥氏体及其碳含量有关。
In order to develop TRIP steel for super high strength automobile with good strong plastic matching, this test steel is designed. CCT-AY-Ⅱ continuous annealing simulator was used to study the influence of isothermal temperature in different bainite regions on microstructure and properties of test steel. The Ac1, Ac3 and Ms, Mf points of the test steel were measured by DIL 805A dilatometer. Tensile testing machine was used to measure the mechanical properties of the test steel. The microstructure and residual austenite of the test steel were observed by SEM, EBSD and XRD techniques. The results show that the tensile strength and yield strength of TRIP steel reach to 1114 MPa and 485 MPa respectively when the temperature is 800 ℃ and the isothermal temperature is 410 ℃. The elongation can be Up to 20%. The yield strength of the test steel is mainly determined by the ferrite, and the tensile strength and elongation are mainly related to bainite, retained austenite and its carbon content.