Q500q桥梁钢在不同冷却方式下的连续冷却转变行为  

Continuous Cooling Transformation Behaviors of Q500q Bridge Steel under Different Cooling Modes

作　　者：冯路路 FENG Lulu(School of Mechanical Engineering,Jingchu University of Technology,Jingmen 448000,China)

机构地区：[1]荆楚理工学院机械工程学院

出　　处：《机械工程材料》2019年第8期23-26,34,共5页Materials For Mechanical Engineering

基　　金：湖北省自然科学基金资助项目(2018CFB304);湖北省教育厅科学研究计划项目(Q20174301);荆门市科技计划项目(2018YFYB054)

摘　　要：利用Gleeble-2000型热模拟试验机在两种冷却方式下对Q500q桥梁钢的冷却转变行为进行研究,一种冷却方式为以恒定的冷却速率(1,4,8,16,32℃·s^-1)从900℃冷却至300℃(恒速冷却),另一种方式为以一定的冷却速率(同前)从900℃冷却至650℃后再冷却速率减半冷却至300℃(分段冷却)。结果表明:在恒速冷却条件下,当冷却速率在1~4℃·s^-1时,试验钢得到多边形铁素体+珠光体组织,当冷却速率在8~16℃·s^-1时得到贝氏体组织,冷却速率增至32℃·s^-1时得到马氏体组织;在分段冷却条件下,当中温区(650~300℃)冷却速率在0.5~4℃·s^-1时试验钢发生铁素体和珠光体转变,多边形铁素体数量较多,当中温区冷却速率在8~16℃·s^-1范围内发生贝氏体转变;与恒速冷却方式下的相比,贝氏体转变的终了温度升高,贝氏体转变区间缩小,贝氏体晶粒的细化程度降低。Cooling transformation behaviors of Q500 q bridge steel by two cooling modes were studied with Gleeble-2000 thermal simulation machine.One cooling mode method(constant cooling)was cooling from 900℃to300℃ at constant cooling rates(1,4,8,16,32 ℃·s^-1)and the other cooling mode(subsection cooling)was cooling from 900 ℃ to 650 ℃ at constant cooling rates(ditto)and then to 300 ℃ at halving cooling rates.The results show that under constant cooling conditions,the steel had a structure of polygonal ferrite+pearlite at the cooling rates of 1-4 ℃·s^-1,a structure of bainite at the cooling rates of 8-16 ℃·s^-1,and a structure of martensite at the cooling rates of 32 ℃·s^-1.Under subsection cooling conditions,the ferrite and pearlite transformation occurred at the cooling rates in the intermediate temperature range(650-300℃)of 0.5-4℃·s^-1,and the amount of polygonal ferrite was relatively large;the bainite transformation occurred at the cooling rates in the intermediate temperature range(650-300 ℃)of 8-16 ℃·s^-1.Compared with those by constant cooling method,the bainite transformation end temperature increased,the transformation region was reduced,and the grain refinement degree of bainite decreased.

关 键 词：Q500q桥梁钢 中温区 连续冷却转变 分段冷却 

分 类 号：TG142[一般工业技术—材料科学与工程]