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采用EBSD和TEM对不同超快速连续退火条件下的低Si系Nb-Ti微合金化TRIP钢进行了显微组织观察,并探讨了拉伸性能.结果表明,100℃/s的加热速率和短时保温制度,使铁素体晶粒细化,并保留了热轧过程中的弥散细小的微合金元素碳氮化物析出,因此提高了钢的强度和塑性.缓冷制度对消除钢的屈服平台有显著作用,而强度有所下降;钢的强度随着退火温度的升高而升高.退火温度在830℃时,残余奥氏体形貌多呈膜状结构与贝氏体铁素体板条相伴出现,使钢的强度和塑性达到了最佳的配合:抗拉强度748 MPa,屈服强度408 MPa,均匀延伸率21.3%,加工硬化指数0.27,强塑积15932.4 MPa·%.
The microstructure of low-Si Nb-Ti microalloyed TRIP steel under different ultra-rapid continuous annealing conditions was investigated by EBSD and TEM, and the tensile properties were discussed. The results show that the heating rate of 100 ℃ / s and short When the insulation system, the ferrite grain refinement, and retained the hot rolling process of fine micro-alloying elements of carbonitride precipitation, thereby enhancing the strength and ductility of steel. Slow cooling system to eliminate the steel yield platform Has a significant effect, while the strength decreased; the strength of steel increased with the annealing temperature.At the annealing temperature of 830 ℃, the residual austenite morphology was mostly film-like structure and bainitic ferrite plate The results show that the best combination of strength and ductility of steel is reached: tensile strength 748 MPa, yield strength 408 MPa, uniform elongation 21.3%, work hardening index 0.27 and strong plastic product 15932.4 MPa ·%.