通过MMS-200热模拟试验机测定了35CrMo模具钢在不同冷却速度连续冷却时的膨胀曲线,检测了显微组织及硬度,同时研究了组织转变和硬度变化规律.结果表明:当冷却速度为0.1~2 ℃/s时,随着冷却速度加大,显微组织由P+F转变为P+F+B,组织中P和F含量减少,B含量增多,硬度从HV250升高至HV388;B组织在冷却速度大于0.4 ℃/s时开始出现;当冷却速度为2~15 ℃/s时,显微组织由B+M转变为M,硬度由HV389升高至HV598.%The dilatometric curves of continuous cooling at different cooling rates are determined on MMS-200 thermal simulation testing machine,the microstructure and hardness are detected and the microstructure transformation and hardness changes of 35CrMo mould steel during continuous cooling are studied.The results show when the cooling rate is between 0.1 and 2 ℃/s,the microstructure transforms from P+F to P+F+B and hardness increases from HV250 to HV388 with increasing cooling rate,but the volume of bainite increases while the volume of pearlite and ferrite decreases.When the cooling rate is over 0.4 ℃/s,bainite initiates to form in the microstructure.When the cooling rate is between 2 and 15 ℃/s,the microstructure changes from B+M to M,the harndess increases from HV389 to HV598.
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