液态模锻2A50特种车辆轮盘冷隔缺陷的成因与防治

Causes and Prevention of Cold Shut Defects in 2A50 Special Vehicle Wheels Produced by Molten Metal Die Forging(MMDF)Process

对液态模锻2A50铝合金负重轮轮盘的冷隔产生进行了分析,表明其起源于轮缘周表面晶界处,并且向内部扩展。冷隔产生的主要原因是铝液紊乱,波动至下模外套直壁上,下压过程中,铝液难以冲破这层表面层,于是形成冷隔。通过缓冲滤渣漏斗工装、适当调节导流槽铝液流速、增加捞渣工序等措施,减少了铝液表面氧化膜的数量,使铝液平稳填充,杜绝铝液波动,从而消除冷隔的产生。

The causes of cold shut of 2A50 aluminum alloy wheel hub produced by the molten metal die forging process,MMDF for short,were analyzed.The result shows that the cold shut originates from the grain boundary of the wheel flange surface and extends to the inside.The main reason for forming the cold shut is that the aluminum liquid fluctuates to the lower mold wall due to disorder.During the pressing process,it is difficult for the aluminum liquid to break through this surface layer,and thus a cold shut is formed.By buffering the filter residue funnel tooling,appropriately adjusting the flow rate of the aluminum liquid in the diversion tank,and increasing the oxides removal process,the number of oxide films on the surface of the aluminum liquid is reduced,the aluminum liquid is filled smoothly and its fluctuation is eradicated,and thus the generation of cold shut is eliminated.