摘要
在Gleeble-3800热模拟机上测定了含微量Mo元素CL60钢在不同冷却速度下连续冷却时的膨胀曲线,并采用金相-硬度法,测定了该钢的连续冷却转变曲线(CCT曲线),研究了冷却速度对其显微组织演变以及硬度的影响。结果表明:当冷却速度小于1℃/s时,实验钢的转变产物为先共析铁素体和珠光体组织;当冷却速度增加到2℃/s时,开始发生贝氏体转变;当冷却速度增加到5℃/s时,开始发生马氏体转变;冷却速度在5~10℃/s的范围内时,转变产物为少量铁素体、珠光体、贝氏体和马氏体所组成的混合组织;当冷却速度为15℃/s时,先共析铁素体消失;当冷却速度为20~40℃/s时,转变产物为珠光体和马氏体混合组织;当冷却速度大于50℃/s时,转变产物全部为马氏体组织。随着冷却速度的增大,实验钢的硬度逐渐增大。尽管Mo元素的加入能细化珠光体片间距,但加Mo元素CL60钢在生产过程中得到理想组织的条件更加苛刻。为避免贝氏体、马氏体等非理想组织出现,不同部位的冷却速度须严格控制在2℃/s以下。
The expansion curves of CL60 steel with trace Mo element under continuous cooling at different cooling rates were measured on the Gleeble-3800 thermal simulator,and the continuous cooling transformation curves(CCT curves)of the steel were measured by metallographic-hardness method.The effect of cooling rate on microstructure evolution and hardness of the steel was studied.The results show that when the cooling rate is less than 1℃/s,the transformation products of the steel are preeutectic ferrite and pearlite,and the bainite transformation begins to occur when the cooling rate increases to 2℃/s.When the cooling rate increases to 5℃/s,the martensitic transformation occurs,and when the cooling rate is in the range of 5-10℃/s,the transformation products are composed of a small amount of ferrite,pearlite,bainite and martensite.When the cooling rate is 15℃/s,the preeutectic ferrite disappears,and when the cooling rate is 20-40℃/s,the transformation products are pearlite and martensite,and when the cooling rate is more than 50℃/s,the transformation product is all martensite.With the increase of cooling rate,the hardness of the experimental steel increases gradually.Although the addition of Mo element can refine the spacing of pearlite pieces,the conditions for obtaining ideal microstructure of the CL60 steel with Mo element in the production process are more stringent.In order to avoid the appearance of non-ideal microstructure such as bainite and martensite,the cooling rate of different parts of the steel must be strictly controlled below 2℃/s.
作者
孔昌昌
秦凤明
张晓峰
党淑娥
陈慧琴
KONG Chang-chang;QIN Feng-ming;ZHANG Xiao-feng;DANG Shu-e;CHEN Hui-qin(School of Materials Science and Engineering,Taiyuan University of Science and Technology,Taiyuan320024,China;Technology Center,Tai Yuan Heavy Insdustry Equipment Co Ltd,Taiyuan320024,China)
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2019年第8期138-144,共7页
Transactions of Materials and Heat Treatment
基金
山西省重点研发计划重点项目(201703D111005)
山西省科技攻关计划(工业)项目(201603D121006-2)
关键词
CL60钢
膨胀法
金相-硬度法
CCT曲线
CL60 steel
dilatometric test
metallographic-hardness method
CCT curve
