超快冷速对钒钛微合金化超高强冷轧板组织性能的影响

超高强冷轧板生产中连续退火工艺十分重要,其快冷阶段的冷却速度对产品性能有较大的影响。本文是在实验室条件下对钒钛微合金化超高强冷轧板连退冷却工艺中快冷阶段冷却速度对产品性能影响的研究,实现抗拉强度达到1 000 MPa。实验中将快冷速度设置为20,50,200,500和1 000℃/s,利用光学显微镜、SEM、TEM组织观察和力学性能测试等方法,研究发现:随着快冷速度增加,铁素体和马氏体晶粒细化,马氏体比例增加且趋于板条状;抗拉强度、屈服强度、屈强比均增加,而延伸率和强塑积不断降低。

Effect of ultra-fast cooling rate on microsturcture and mechanical properties of vanadium titanium micro alloying ultra-high strength cold-rolled sheet

In the production of ultra-high strength steel,continuous annealing process plays a critical part,of which the core technology is fast cooling technique. The effect of cooling rate on mechanical properties of va-nadium titanium micro-alloying ultra-high strength cold-rolled sheet were studied in this paper. The cold-rolled sheet is required to be 1 000 MPa grade high strength steel. The fast cooling rate were set as 20℃/s,50℃/s, 200℃/s,500℃/s and 1 000℃/s. Optical microscope,scanning electron microscopy (SEM),transmission electron microscopy (TEM) and mechanical properties tests were employed. The results showed:grains of mar-tensite and ferrite were refined as the increases of the cooling rate;the proportion of martensite increased and the martensite gradually tends to be lath-shaped;the tensile strength,yield strength and yield ratio increased;elongation and product of strength and elongation decreased.