摘要
借助Gleeble-1500D热模拟试验机,根据温度传感器实时提取出来的温度-时间曲线计算冷却速度,采用分段冷却的方式,得到了铸造低合金Cr-Mo钢的连续冷却转变CCT曲线,并对其进行了分析。结果表明,铸造低合金Cr-Mo钢的Ac3,Ac1和Ms分别为925,765和485℃。冷却速度小于3℃/s时,发生奥氏体向贝氏体的转变;冷却速度为3~18℃/s时,发生奥氏体向珠光体和贝氏体的转变;冷却速度为18~50℃/s时,出现马氏体;冷却速度大于50℃/s时,只发生马氏体转变。CCT曲线中珠光体和贝氏体两大转变区相互分开,Ms线右端下降,没有先共析铁素体转变区。随着冷却速度的增加,硬度值逐渐增大;随着冷却速度的减小,元素分布趋于均匀,较慢的冷速有利于生成细小均匀的室温组织。
According to temperature-time curve,by using the way of segmented cooling, CCT diagram of low-alloy Cr-Mo refractory steel is determined at Gleeble-1500D thermal simulation testing machine. The results show that Ac3, AC1 and Ms of the steel are 930, 760 and 485 ℃, respectively. The bainite can be obtained when the cooling rate is lower than 3 ℃/s; the pearlite and bainite can be obtained from 3 ℃/s to 18 ℃/s. When the cooling rate in the range of 18-50 ℃/s, the structure at room temperature including M. When the cooling rate above 50 ℃/s, only the martensite transformation occurred. CCT curve shows that the pearlite and bainite transformation region is separated, there is no region of proeutectoid ferrite, and the Ms line down the right end. With the increase of cooling rate, the hardness value increase gradually. With the decrease of cooling rate, the elements distribute uniformly. The slow cooling rate is helpful to obtain the tiny and uniform microstructure.
出处
《铸造技术》
北大核心
2017年第11期2602-2605,共4页
Foundry Technology
