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在Gleeble-1500D热模拟试验机上,测定了ST52-3G钢在不同冷却速率下过冷奥氏体连续冷却的膨胀曲线,利用膨胀法结合金相-硬度法,绘制了试验钢过冷奥氏体连续冷却相转变曲线(CCT曲线),研究了试验钢组织及硬度与冷却速率之间的影响规律。结果表明,试验钢的Ac_1和Ac_3分别为760℃和940℃;微观组织主要有铁素体、珠光体和贝氏体。较慢冷却速率时发生铁素体和珠光体转变,其中铁素体含量较多;当冷却速率大于20℃/s时发生贝氏体转变;随着冷却速率的提高,各组织或晶粒变细,试验钢的硬度随着冷却速率的增加呈先快后慢趋势。
On the Gleeble-1500D thermal simulator, the expansion curve of ST52-3G steel under continuous cooling at different cooling rates was measured. Using the expansion method combined with the metallographic-hardness method, the experimental austenite Continuous cooling phase transition curve (CCT curve), the experimental steel and hardness and cooling rate between the impact of the law. The results show that the Ac_1 and Ac_3 of the test steel are 760 ℃ and 940 ℃ respectively. The microstructure mainly includes ferrite, pearlite and bainite. Ferrite and pearlite transformation occurred at slower cooling rate, with more ferrite content. When the cooling rate was greater than 20 ℃ / s, bainite transformation occurred. With the cooling rate increasing, Fine, the hardness of the test steel with the cooling rate increased first and then slow trend.