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结合膨胀法和金相-硬度法,利用Gleeble-1500D热模拟机测定了42CrMoA钢的临界点Ac1、Ac3和Ms点,测定了该钢在不同冷却速度下连续冷却时的膨胀曲线,相转变点;分析了连续冷却过程中过冷奥氏体转变过程及转变产物的组织形貌;测定了不同冷却速度下相转变后的硬度,获得了该钢过冷奥氏体连续冷却相转变曲线。结果表明,当冷却速度小于0.1℃/s时,转变产物为铁素体和珠光体组织;当冷却速度0.2～0.6℃/s时转变产物是铁素体、珠光体、贝氏体的混合组织;当冷却速度为0.7～17℃/s时,转变产物是贝氏体和马氏体的混合组织;当冷却速度大于20℃/s时,转变产物为完全马氏体,此次实验并没有获得完全贝氏体。
The critical points Ac1, Ac3 and Ms of 42CrMoA steel were measured by Gleeble-1500D thermal simulator combined with expansion method and metallography-hardness method. The expansion curves of the steel were measured when the steel was continuously cooled at different cooling rates. The phase transition point The process of supercooled austenite transformation during continuous cooling and the microstructure of the transformed product were analyzed. The hardness after the phase transformation at different cooling rates was measured and the continuous cooling phase transformation curve of the subcooled austenite was obtained. The results show that when the cooling rate is less than 0.1 ℃ / s, the transformation products are ferrite and pearlite. When the cooling rate is 0.2-0.6 ℃ / s, the transformation products are mixed ferrite, pearlite and bainite When the cooling rate is 0.7-17 ℃ / s, the transformation product is a mixed microstructure of bainite and martensite. When the cooling rate is more than 20 ℃ / s, the transformation product is completely martensitic. Get complete bainite.