摘要
零件快速可控地冷却,对于许多金属获得最佳力学性能是很重要的.这需要通过对淬火剂的搅拌或强制循环来缩短冷却时间.如果没有搅拌,淬火液自然热交换和蒸发会限制零件表面上通过液膜边界层的传热速率.在这种情况下,变更淬火剂的温度对冷速只有很小的影响.搅拌程度的加强,大大减少了液膜边界层中热流的阻力.淬火系统的搅拌可用机械方式使零件移动通过淬火槽,或淬火液再循环流动,或机械地引起液体搅拌/循环.冷速的控制是很重要的.机械搅动提供最佳的在最低能耗成本下的成就.本文介绍叶轮搅拌系统、搅拌原理和搅拌机选型的实用建议.
Quenching operations have demonstrated that rapid controlled cooling of the parts is an essential element of the formation of optimum mechanical properties of metals.Agitation,or forced circulation of the quenchant,is required to shorten the cooling times.Without agitation,natural convection of the quenchant and quenchant vaporization limit the heat transfer rate through the fluid film boundary layer at the surface of the part.Under these conditions,changes in the quenchant medium temperature will have little effect on the cooling rate.Obtaining a forced convection fluid regime greatly reduces the resistance to heat flow at the fluid film boundary layer.This can be accomplished by mechanically moving the parts through the bath,pumping to recirculate the quenchant,or mechanically inducing agitation/circulation of the fluid.Where control over the cooling rate is important,mechanical agitation provides the best performance at the lowest energy cost.This article will describe propeller agitation systems,principles of agitation,and practical recommendations for mixer selection.
出处
《金属热处理》
CAS
CSCD
北大核心
1993年第11期24-29,共6页
Heat Treatment of Metals
关键词
淬火槽
搅拌器
quench tank
propeller agitation system
