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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。
With the aid of Gleeble-1500D thermal simulation tester, the cooling rate was calculated based on the temperature-time curve extracted from the temperature sensor in real time. The CCT curve of the continuous cooling transformation of the cast low alloy Cr-Mo steel was obtained by the segmented cooling method. Analyzed. The results show that Ac3, Ac1 and Ms of cast low alloy Cr-Mo steel are 925, 765 and 485 ℃, respectively. When the cooling rate is less than 3 ℃ / s, the transformation of austenite to bainite occurs. When the cooling rate is 3 ~ 18 ℃ / s, the transformation from austenite to pearlite and bainite occurs. The cooling rate is 18 ~ At 50 ℃ / s, martensite appears; when the cooling rate is more than 50 ℃ / s, only martensitic transformation occurs. CCT curve of pearlite and bainite two transition zone separated from each other, Ms line right down, no pro-eutectoid ferrite transformation zone. With the increase of the cooling rate, the hardness value gradually increases; with the cooling rate decreases, the element distribution tends to be uniform, the slower cooling rate is conducive to the formation of small and uniform room temperature tissue.