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提高铝合金铸件致密性的一种有效工艺是压力下结晶,即铸件在结晶凝固期间,使之处于大于大气压力的环境中,迫使液体金属在枝晶间流动来补充显微缩孔和缩松。一般认为这项工艺只适用于较厚大的铸件,对薄壁铸件因凝固过快而无效。航天、航空工程中许多铝合金铸件的断面为薄壁或超薄铸,对铸件内部组织的致密性有一定要求。本文综合了液体金属和铸型的热物性,从理论和实验方面研究了薄壁铸件适合于压力结晶的基本条
An effective technique to increase the densification of aluminum alloy castings is to crystallize under pressure, that is, during the solidification of the castings, the castings are subjected to a pressure greater than atmospheric pressure, forcing liquid metal to flow between the dendrites to replenish the microcracks and shrinkage . Generally believed that the process is only applicable to thicker castings, thin castings due to solidification too fast and ineffective. Many sections of aluminum alloy castings in aerospace and aviation engineering are thin-walled or ultra-thin castings, which have certain requirements on the compactness of the internal structure of castings. In this paper, the thermophysical properties of liquid metals and molds are summarized. The basic rules of thin-walled castings suitable for pressure crystallization are studied theoretically and experimentally