将 C- Si- Mn 系 TRIP 钢通过完全淬火和两相区退火相结合的工艺,得到一种以退火马氏体为基体的 TRIP 钢(简称TAM 钢),并对比分析了 TAM 钢在不同温度退火后的显微组织和力学性能。结果表明,TAM 钢经退火后的显微组织特征为精细规整的板条退火马氏体基体、片状残余奥氏体和贝氏体/马氏体组成的混合组织。这种组织降低了基体的硬度以及基体和第二相之间的强度比,减少了基体的位错密度。随着退火温度的提高,退火马氏体基体的板条形态逐渐消失,新生马氏体/贝氏体的团状混合组织逐渐增多。当退火温度为780℃时,综合力学性能优异,抗拉强度为1130 MPa,延伸率可达20%,强塑积为22600 MPa·%。当退火温度较低时,残余奥氏体主要以片状存在于退火马氏体板条间,有利于 TRIP 效应的发生。
Special TRIP steel with annealed martensite matrix (TAM steel) was produced by fully quenching and annealing in the two-phase region with the C- Si- Mn chemical composition of common TRIP steel. The microstructure and mechanical properties of TAM steel annealed at different temperatures were investigated by thermal dilatometry, tensile testing, optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. It is found that the microstructure of TAM steel consists of a uni-form fine annealed martensite matrix and an interlath second phase of retained austenite and bainite/ martensite, which contribute to lowering the matrix’s hardness and the strength ratio of matrix to second phase as well as decreasing the dislocation density. As the an-nealing temperature rises, the mixed blocky microstructure of newly formed martensite/ bainite gradually increases, while the lath-like morphology of annealed martensite progressively disappears. Excellent mechanical properties are obtained when the annealing tempera-ture is 780 ℃ , with the tensile strength, the elongation, and the product of strength and ductility up to 1130 MPa, 20% , and 22600 MPa·% , respectively. When the annealing temperature is relatively low, retained austenite mainly exists between annealed martensite laths in film-form and is conducive to the occurrence of TRIP effect.