决定淬火工件表面冷却速度的两个新因素

用标准探棒检测出的油或者水的冷却速度曲线既不能反映探棒表面的冷却情况,也不能用来推测工件表面的冷却过程。因此,应直接观测工件的冷却过程。淬火冷却过程的直接观测和研究发现,除了淬火介质的冷却能力和工件某部位的有效厚度之外,不同工件表面蒸气膜内气体的流动状况和工件表面从蒸气膜向沸腾冷却方式转型的次序,对工件表面的冷却速度和整个工件的冷却均匀性都有很大影响。业已揭示了后两种新因素影响工件冷却速度和冷却均匀性的基本规律,从而可以在淬火冷却过程中对同一工件表面的不同部位的冷却速度分别加以控制,这种控制技术被称为精细淬火冷却技术。

New Factors Determining the Cooling Rate of WorkPiece Surface During Quenching

The cooling rate curves of oil or water detected by a standard probe can neither represent cooling status of the probe surface nor be used to infer cooling process of the workpiece surface.In view of the above-mentioned facts,the cooling process of workpiece should be observed directly.It is apparent from direct observation and investigation of the quenching process that apart from the cooling power of quenchant and the effective thickness of a certain position of workpiece the gas flow within vapor blankets on different workpiece surfaces and the sequence of conversion of vapor blanket stage to boiling stage on workpiece surface will exert a significant influence on the cooling rate of workpiece surface and the cooling uniformity of whole workpiece.Basic law of such two new factors influencing the cooling rate and uniformity of the workpiece has been clarified,and consequently the cooling rate of different positions at a workpiece surface may be controlled respectively during the quenching,which is known as fine quenching technology.