关键词：钢铁；铌钛微合金化钢；CCT曲线；相变
摘 要：Continuous cooling transformation (CCT) curves of deformed austenite (A) of Nb-Ti microalloying high strength steel were measured using Gleeble-3800 thermo-mechanical simulator,and corresponding transformation and structure were analyzed,and the effects of cooling rate on the tested steel's mechanical property were studied.The resultes showed that the Ar3 transformation point decreased with increasing cooling rate after hot-rolling.The morphology of ferrite (F) grains changed from polygonal to lath,and the pearlite (P) colonies became more fine with increasing cooling rate.The quantity of ferrite and pearlite decreased,and the quantity of bainite (B) and martensite (M) increased.Then the hardness of Nb-Ti micro-alloyed steel is increased along with the increasing cooling rate,which may owing to the reasons that the hardness of ferrite and pearlite is far smaller than that of bainite and martensite,and the grain refinement causes the hardness increasing.