极地海洋平台用Nb-V微合金化热轧H型钢TMCP工艺

TMCP process of Nb-V micro-alloyed hot rolling H-beam steel for polar offshore platform

在实验室利用Gleeble-3500热模拟试验机对Nb-V微合金化H型钢进行了连续冷却转变与形变热模拟试验,研究了形变温度和冷却速度对试验钢组织和力学性能的影响。结果表明：连续冷却转变过程中,冷速为1℃/s时,组织中开始出现少量贝氏体;冷速大于7℃/s时,不发生珠光体转变;冷速为15℃/s时,不发生铁素体转变。形变热模拟条件下,冷速≤1℃/s时,形变未改变试验钢的组织类型,其组织均为铁素体＋珠光体;冷速为5～10℃/s时,形变显著改变试验钢的组织形态;形变温度越低,其组织中铁素体含量越高,铁素体与贝氏体组织越细小;形变温度为800～850℃,冷速控制在3～5℃/s时,试验钢可获得强韧性较好的细小准多边形铁素体与贝氏体的复合组织。

Continuous cooling transformation and thermo-mechanical simulation of the Nb-V micro-alloying H-beam steel were conducted to study the influence of deformation temperature and cooling rate on microstructure and mechanical properties of the tested steel by using a Gleeble-3500 thermal-mechanical simulation machine. The results show that a small amount of bainite begin to appear in the microstructure when the cooling rate is 1 ℃/s, no pearlite transformation is present when the cooling rate is greater than 7 ℃/s, and the ferrite transformation does not occur when the cooling rate is 15 ℃/s during continuous cooling transformation. However, under the condition of thermo-mechanical deformation simulation, The microstructure can’t be changed by the deformation and is still composed of ferrite and pearlite when the cooling rate is less than or equal to 1 ℃/s. The cooling rate is in the range of 5-15 ℃/s, the microstructure of the tested steel is significantly changed. And the lower deformation temperature, the content of ferrite is the higher and the ferrite and bainite is the smaller. Microstructure of fine quasi polygonal ferrite and bainite with better strength and toughness can be obtained when the deformation temperature is in the range of 800-850 ℃ and the cooling rate is controlled in the range of 3-5 ℃/s.