研究了挤压铸造过程中机械振动对A356铝合金材料显微组织与力学性能的影响规律,并对机械振动击碎枝晶的作用机理进行了阐述.结果表明:施加机械振动能够有效地消除材料缩松缩孔及断面裂纹,减少甚至消除挤压铸造铝合金铸锭的微观孔洞,细化晶粒组织,使得组织更加均匀;挤压铸造凝固初期,机械振动能够在很大程度上破碎二次枝晶臂,增加材料的形核率;试验值与理论值的对比分析表明,Kirkwood模型具有更高的精度;机械振动能够提高材料的力学性能,相较于重力铸造与无振动挤压铸造而言,所得铸件的抗拉强度与延伸率均有一定提高.%In this paper, the effects of mechanical vibration on the microstructure and mechanical properties of A356 aluminum alloy were experimentally investigated , and the mechanism of dendrite breaking under the action of mechanical vibration was explored .The results show that ( 1 ) mechanical vibration helps to effectively eliminate material's shrinkage hole and section crack during the squeeze casting , reduce or even eliminate the micro casting pores in aluminum alloy and refine the grain structure , thus resulting in more compact microstructure;( 2 ) in the initial solidification stage of the squeeze casting , to a large extent , mechanical vibration can break the secondary dendrite arms and increase the nucleation rate of materials;(3) the Kirkword model is of higher accuracy which is proved by a comparison between the experimental and the theoretical results;and (4) as compared with the gravity casting and the squeeze casting without mechanical vibration , the casting with mechanical vibration significantly im-proves the mechanical properties of aluminum alloy and achieves higher tensile strength as well as more elongation .
展开▼
