含钒0.2C-0.5Si-0.08P-Mn TRIP钢连续冷却过程中的相变行为

Continuous Cooling Transformation Behaviour of V-Bearing 0.2C-0.5Si-0.08P-Mn TRIP Steel

通过热模拟实验研究了含钒0.19%的0.2C-0.5Si-0.08P-Mn TRIP钢连续冷却过程中的相变行为.实验结果表明:奥氏体未再结晶区进行50%的大变形,使随后连续冷却过程中的铁素体开始相变温度Ar3提高42～58℃;相同冷却速度下,尤其是当冷速小于20℃/s时,变形促进铁素体的形成,而使贝氏体形核率降低;钒的氮化物和碳化物在铁素体晶粒和晶界处弥散析出,无论变形或未变形条件下,冷速0.5℃/s时,析出粒子尺寸在2～5nm范围内,只有极少量尺寸约为～20nm的较大析出粒子.

The continuous cooling transformation（CCT）behaviour was investigated for the 0.2C-0.5Si-0.08P-Mn TRIP steel with 0.19% vanadium on a thermo-simulator.The results revealed that the starting transformation temperature of ferrite（Ar3）is increased by 42～58？℃ during subsequently continuous cooling after the deformation rate has been up to 50% in the zone where the austenite has not been recrystallized.At the same cooling rate especially it is lower than 20？℃/s,the deformation of austenite stimulates the formation of ferrite with the bainitic nucleation rate reduced.The vanadium nitrides and vanadium carbides both disperse and precipitate within ferritic grains or at grain boundaries,and most of the precipitated particle sizes are in the range from 2 to 5？nm at the cooling rate 0.5？℃/s,regardless of whether the austenite is deformed or undeformed.It was found in specimens that only a few precipitate particle sizes are about 20？nm.