研究了快速加热连续退火工艺对V微合金化低Si含P系TRIP钢显微组织特征与力学性能的影响. 结果表明, 快速连续退火过程中, 随着退火温度的升高, 拉伸强度增加明显, 然而为了保证其综合性能, 并不能一味地提高其临界退火温度.加热速率80℃/s, 退火温度为880℃时, 残余奥氏体形态不仅仅局限于细小的块状结构, 而且在贝氏体铁素体板条间能观察到大量的薄膜状残余奥氏体. 细小、弥散的V(C, N))分布于铁素体或贝氏体基体中, 大部分析出粒子直径在4-9 nm之间, 实验钢具有优异的强度与塑性配合: Rm=1010 MPa, RP0.2=690 MPa, δ=23.6%, n=0.27, r=1.17, 强塑积达到23836 MPa?%. 退火温度过高或过低, 都会减少残余奥氏体的体积分数、改变其形貌并增大其尺寸, 导致综合力学性能下降.
The effects of rapid heating continuous annealing on microstructure and mechanical properties of ultra–high strength and low silicon TRIP steel containing phosphorus and vanadium were investigated. The results show that the yield and tensile strengths are increased with increasing intercritical annealing temperature during rapid continuous annealing. However, the intercritical annealing temperature can not increase blindly to ensure its excellent combined mechanical properties. When the heating rate is 80 ℃/s and intercritical annealing temperature is 880 ℃, the retained austenite not only contains fine blocky structure, but also a large amount of interlath retained austenite films. A great amount of V(C, N) precipitates exists within ferritic matrix, and the sizes of most of the precipates are in the range from 4 to 9 nm. The tested steel has excellent mechanical properties: Rm=1010MPa, RP0.2=690MPa, δ=23.6%, n=0.27, r=1.17, the product of strength and ductility (Rm×δ) is 23836 MPa·%. If the intercritical annealing temperature is too high or too low, the comprehensive mechanical properties will be deteriorated since the volume fraction of retained austenite reduces, morphology changes and its size increase.
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