Two New Factors Determining the Cooling Rate of Work Piece Surface during Quenching
Beijing Huali Fine Chemical Co. Ltd., Beijing 102200, China
Abstract: The temperature cooling rate curves of oil and water detected by a standard probe can neither reflect the cooling status of the probe surface nor can they be used to make deductions about the cooling process of the work piece surface. In order to gain information about the cooling status of a work piece surface, the cooling process of the sample should be observed directly. By studying and summarizing several observation results, it is found that apart from two factors (the cooling capability of the quenching medium and the effective thickness of a certain surface point), the gas flow within the vapor blankets of different surfaces and the sequence of transfer from vapor blanket stage to boiling stage could both greatly influence the cooling rate of a given surface point and then the cooling uniformity of the whole work piece. The effect mechanisms of the two new factors on the cooling rate and uniformity of the work piece is investigated in this paper. According to the effect law of the new factors, the cooling rates of different parts of the work piece surface can be controlled separately in the quenching process. This kind of control technique is called fine quenching technology.
Keywords: quenching cooling, liquid quenchants, detecting method of cooling features, analog computation of quenching process, determination of surface heat flux, fine quenching technology.