过共晶铝硅合金组织对切削加工性能的影响

EFFECT OF STRUCTURE OF HYPEREUTECTIC Al Si ALLOY ON MACHINABILITY

为分析过共晶铝硅合金组织对其切削加工性能的影响，对两种化学成分相同但是组织结构不同的过共晶铝硅合金进行了切削试验研究并探讨了其切削机理。试验结果表明：过共晶铝硅合金经变质处理后组织中初晶硅的大小、形状和分布状况对切削刀具寿命和合金的切削加工表面质量影响极大，具有细小、分散而形状圆钝化初晶硅的合金有比较好的切削性能。造成这种影响的主要原因在于细小的硅粒比较容易协同基体塑性变形和被刀具压入切屑和已加工表面，而粗大的硅块往往发生解理破碎、脱落和位移，直接与刀具发生强烈摩擦并使已加工表面存留许多缺陷。

In order to analyze the effect of structure of hypereutectic Al Si alloy on its machinability, the cutting test to two hypereutectic Al Si alloys which have the same chemical composition but different structures is made and their cutting mechanism is studied. The results show that, after transformation the size, shape and distribution of primary silicon in hypereutectic Al Si alloy have a serious effect on the tool life and the machined surface quality of the alloy, the alloy whose primary silicon is fine, spread and dull angular has a better machinability. It is considered as the main reason that the fine silicon is easier to be pressed into the matrix and to cooperate with the matrix deformation in the machining of alloy, but the coarse silicon breaks, drops out and displaces usually during the machining, which results in strenuous friction between the tool and the work and various defects in machined surface.