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针对目前高碳高硅低温贝氏体(纳米结构贝氏体)相变速度缓慢的现状,采用贝氏体相变热力学理论分析主要合金元素对低温贝氏体相变驱动力的影响,设计了新型纳米结构贝氏体钢成分0.83C-2.44Si-0.43Mn-0.73Al.利用膨胀仪研究该成分贝氏体钢在不同温度下的相变整体动力学,综合使用扫描电子显微镜、X射线衍射、电子背散射衍射等方法研究热处理工艺对实验钢组织和力学性能的影响.结果表明,350℃等温转变贝氏体的抗拉强度为1401 MPa,延伸率为42.21%,强塑积可达59136 MPa·%,在室温拉伸过程中发生明显的相变诱导塑性效应;230℃等温转变组织中贝氏体铁素体片层厚度小于100 nm,抗拉强度达2169 MPa.
In view of the present situation of slow phase transformation of high-carbon and high-silicon low-temperature bainite (nanostructured bainite), the influence of main alloying elements on the driving force of low-temperature bainite transformation was analyzed by using bainite transformation thermodynamics theory. The new nanostructured bainitic steel composition 0.83C-2.44Si-0.43Mn-0.73Al. Using dilatometer study of the composition of bainitic steel at different temperatures, the overall phase transition kinetics, using a combination of scanning electron microscopy, X-ray diffraction , Backscattering electron diffraction (EDS), etc. The results show that the tensile strength of isothermal bainite at 350 ℃ is 1401 MPa, the elongation is 42.21% and the plastic modulus is 59136 MPa ·%. The phase transition induced ductile plastic effect occurred at room temperature. The thickness of bainitic ferrite layer in isothermal transformation at 230 ℃ was less than 100 nm, and the tensile strength reached 2169 MPa.