铝合金铸件出现针孔是常见的一种缺陷。产生的原因是当铸件表面刚凝固时,溶解在铝液中的氢气析出但又跑不出来,因而留在铸件表面层下形成针状小孔,即所谓“针孔”。要去除针孔,首先要排除产生气体的根源。一般产生气体有以下几点原因:1.原材料不干净,带油污或腐蚀的较厉害;2.熔化用的工具未彻底烘 Pinhole aluminum alloy casting is a common defect. The reason for this is that when the surface of the casting just solidifies, the hydrogen dissolved in the molten aluminum is precipitated but does not run out, thus leaving acicular pores under the surface layer of the casting, the so-called “pinhole”. To remove the pinholes, we must first rule out the source of gas. Gas generally have the following reasons: 1. Raw materials are not clean, with oil or more corrosive; 2. Melting tools are not thoroughly baked