Q345钢奥氏体连续冷却转变曲线(CCT图)  

Continuous cooling transformation curve of undercooling austenite about Q345 steel

作　　者：林武[1] 张希旺[2] 赵延阔[1] 李红英[1] 

机构地区：[1]中南大学材料科学与工程学院,长沙410083 [2]湖南省特种设备检测中心,长沙410004

出　　处：《材料科学与工艺》2009年第2期247-250,共4页Materials Science and Technology

摘　　要：研究了Q345钢连续冷却过程中奥氏体转变过程及转变产物的组织和性能，为制定生产工艺提供参考依据．利用膨胀法结合金相-硬度法，得到不同冷却速度连续冷却时的膨胀曲线和相应的金相组织及硬度，用DTA法及膨胀法测定其临界点Ac1、Ac3以及Ms，获得了Q345钢的连续冷却转变曲线（CCT图）．由CCT图和不同冷却速度的显微组织照片可知，当冷却速度比较低时，形成较粗大的块状铁素体和珠光体，当冷却速度大于0．5°C／s时出现贝氏体，形态似针状铁素体，其形成温度在450-600℃左右，当冷却速度大于20℃／s时，发生马氏体转变，马氏体转变点约为400℃．Transformation of austenite and morphology of its product with mechanical property in the continuous cooling process of Q345 steel were investigated in order to provide references for industrial production. Dilatometric curves with corresponding microstructures and hardness of the samples cooled by different cooling rates were obtained by dint of dilatometric change referencing microscopic test and hardness measurement. The critical points at Ac1 , Ac3 along with Ms of Q345 steel were determined by dilatometric test and differential thermal analysis （DTA）. The result indicates that massive morphology of ferrite and pearlite can be easily formed when the cooling rate is relatively low; the bainite, whose formation temperature is about 450 -600°C, appears when the cooling rate is greater than 0.5°C/s, and it exists in the pattern of acicular ferrite; and that martensitic transformation, whose phase transition point is at about 400°C, occurs when the cooling rate is greater than 20°C/s.

关 键 词：Q345钢 热模拟 膨胀法 金相-硬度法 连续冷却转变曲线 

分 类 号：TG151.2[金属学及工艺—热处理]