Computer Simulation Of Quenchant Flow Field In Quenching Tank With Or Without Workpieces

In metallography, the definition of quenching is "the controlled extraction of heat",it is the most important process for components to get required microstructures and proper mechanical. In production, the main cause of reject and reversion of the products is workpiece distortion or inner quality question in quenching. In the factors inducting distortion and cracking the main cause is the non-uniformity in cooling. While the hot workpieces are quenched in the quenching tank, and the distribution of quenchant flow field in it has an crucial influence on the quenching uniformity of the workpiece.Therefore research on the quenchant flow field in the tank not only can optimize the desigen of tank corporeity, agitator system and flow-equalizing equipment, and but also can analyse and predict where the distortion easliy occured by workpiece shap and racking, and then improve the quenching uniformity of workpiece to avoid from large distortion and quenching cracking.In order to study the quenchant flow field in the quencing oil tank used in the workshop, a 3-D model of the tank(effective quenching zoneφ2500mm×3000mm) with real workpiece dimensionescaped dimension error was first established. Aided by the Fluent 6.2——a good-size commercialsoftware the quenchant velocity in the quenching tank without and with workpieces was obtained. The results of simulation and experiments are as following:(1) When the tank is without loading, a "effective quenching zone" will be formed in the middle and top of the tank . After loading of workpieces the distribution of quenchant flow field will produce great chang and the new distribution of it will be formed by the racking mode of the partes and the part shap.(2) When the tank is with loading of geares piled up on the rack, the quenchant velocity on the top and bottom of the rack appears very slow,but the velocity on the edge of the gears is faster than other position.(3) The simulation result of quenchant flow field in the tank with gear shafts standing on a disk showes that: The quenchant velocity is fast and symmetrical around the gear shafts except the inner region of bottom of the gear shafts.(4) A quenching tank with gear rings standing on the disk or rack was selected to simulate the flow field. The simulation result showes that the velocity around the gear rings on the top and middle of the rack is symmetrical , but it is different around gear rings on the bottom of rack.(5) In order to validate the simulation result,a test was conducted,several test bars of 40Cr steel were placed separably on the special spots of rack,according to the correction of core hardness and the hardenability of sample, the quench severity of each spot was found.(6) Through the simulation of the quenchant flow field in the tank with or without workpieces,there distribution and characteristic were obtained. The present work is helpful for design of the tank and the racking of different gears,and could improve the quenching quality of gear and decrease the quenching distortion.