退火时间对超快速加热下热镀锌用TRIP钢组织性能的影响

EFFECT OF ANNEALING TIME ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF HOT-DIP GALVANIZED TRIP-AIDED SHEET STEELS UNDER ULTRA RAPID HEATING

研究了退火时间对超快速加热连续退火工艺下V微合金化低Si含P系热镀锌用TRIP钢显微组织特征与力学性能的影响.结果表明,超快速连续退火过程中,高密度位错以及细小、弥散的V(C,N)分布于基体中,大部分析出粒子直径在4—10 nm之间.残余奥氏体体积分数随着退火时间的延长而增加,但其形貌特征发生改变,随着退火时间延长到90 s时,以厚度在80—120 nm之间的片层状残余奥氏体为主;继续延长到180 s时,残余奥氏体的片层厚度增加至200—600 nm,趋于块状.随着退火时间的延长,拉伸强度逐渐降低,而延伸率和加工硬化指数呈上升趋势;表征强度与塑性综合性能的强塑积由退火时间t=10 s时的23976 MPa.%降低到t=180 s时的23625 MPa.%.

The effects of annealing time on microstructure and mechanical properties of low silicon TRIP steel containing phosphorus and vanadium for hot dip galvanization under ultra rapid heating were investigated. The results show that a high density of dislocations and the vanadium precipitate existe within matrix during ultra rapid continuous annealing, and most of the precipitated particle sizes are in the range from 4 to 10 rim. The volume fraction of retained austenite is increased with increasing annealed time, but the retained austenitic morphology is changed. The interlath retained austenite films with a thickness of 80--120 nm are dominated with increasing annealed time to 90 s; the thickness of interlath retained austenite films is increased to 200 600 nm and tended to block structure continuing to increase the annealed time to 180 s. The yield and tensile strength are decreased with increasing annealed time during ultra rapid continuous annealing, however, the elongation and work harding index are increased; the product of strength and ductility （Rm·δ） is decreased from 23976 MPa.% when annealed time is I0 s to 23625 MPa.% when annealed time is 180 s.