Two New Factors Having Influence on Surface Cooling Rate of Quenched Workpiece

Abstract The cooling processes of standard probes are observed directly, and it is found that all of the measured cooling characteristic curves cannot reflect the actual cooling condition of the probe surface. To know how the surface of a workpiece is cooled, the actual cooling process of the workpiece must be observed. The quench cooling processes of samples in different shapes and sizes are directly observed and video is recorded; the causes for the observed phenomena are discussed. Then, it is found that the flow of gas in the vapor blanket and the order of transition from vapor blanket cooling to boiling cooling at different parts have considerable influences on the surface cooling rate of the workpiece and cooling uniformity of the entire workpiece, in addition to the cooling capacity of the quenching medium and effective thickness of the workpiece. The fundamental rules of these two factors are tentatively revealed. Utilizing these rules, we can aspire to regulate and control the cooling rates on different surfaces of the same workpiece in the quench cooling process.