中厚板辊式淬火机淬火过程的冷却机理

Cooling mechanism during quenching by plate roller quenching machine

针对中厚板辊式淬火机淬火工艺过程,在分析淬火喷水系统射流流场结构及换热特性的基础上,阐明其淬火过程的热交换机理主要为射流冲击换热。并结合实际工况参数,通过模拟分析不同淬火冷却条件对中厚钢板温度场及应力场的影响规律,指出高压淬火区的高强度冷却是板材内部应力产生的主要因素。研究表明辊式淬火机淬火过程的冷却机理在于:在淬火钢板800～500℃的温度区间,采用高压淬火区高强度冷却,有利于钢板获得大于临界淬火速度的高冷却速率,以避免发生其它类型的组织转变;在500℃以下的温度区间,采用低压淬火区慢冷,有利于减小钢板的热应力和马氏体转变过程中产生的组织应力,从而降低钢板在马氏体转变过程中的综合内应力,减小钢板变形倾向。

For plate quenching on roller quenching machine,the quenching water jet flow field structure and local heat transfer characteristics were analyzed.It is revealed that the jet impinging heat transfer is predominant mode during quenching.According to industrial parameters,the effects of different quenching conditions on the plate temperature and stress fields were investigated by numerical simulation.The results indicate that the main influencing factors on the plate internal stresses are the high-intensifyied cooling in high-pressure quenching zone.The cooling mechanism during quenching on roller quenching machine is as follows： the steel plate is cooled in high-pressure quenching zone with high cooling intensity at 800-500 ℃,to keep large temperature gradient on the inside of the plate to ensure high cooling rate to obtain martensite and thus other phase transformation is avoided,and then at temperature blow 500 ℃,the plate is fully cooled in low-pressure zone with lower cooling rate,which is beneficial to decreasing the internal thermal and phase transformation stresses,thus reducing the plate quenching deformation.