Selection of Quench Media Based on Their Cooling Characteristics

摘要

For quenching of steel components, the following effects are expected: (1) high and uniform hardness and adequate hardened depth; (2) no quenching crack; (3) little or no distortion. Proper selection of quench media is a premise for achieving these goals. At present, the cooling characteristics of a quench medium are measured mostly by adopting the international standard (ISO9950), and are illustrated on the cooling rate curve. However, in order to quench a particular workpiece with definite shape, size and property requirements, how to decide an ideal quench medium based on its cooling characteristics? In a workshop one quench tank is usually used to treat a variety of workpieces made from different steels. How can we choose a common quench medium for such varieties? A few research has been done on them, but no systematic practical solutions were proposed. In production, some workpieces were not sufficiently hardened when quenched in oil, while they were cracked when quenched in water. Based on the previous work, this paper will introduce the methods about how to choose proper quench media in accordance with the distribution of cooling rates in a particular workpiece. Further more, the principles of selecting a medium common in use for a variety of workpieces will be suggested.