Effects of Thermal and Pressure Factors on Surface Formation of Cast Alloys

针对薄壁铸件的需要，研究了液态金属在流场中的凝固行为，以加深对铸件表面形成过程的基本认识。(1)薄壁铝合金的流动性：用吸力试验法研究了Al-Si-Cu合金的流动性。研究了截面厚度、吸气压力、模具材料、表面处理、浇注温度和模具气氛等因素对铸件性能的影响。讨论了表面张力对铸铁流动性的影响。(2)铸铁的流动性：研究了断面厚度、浇注温度、孕育处理和吸气压力对铸铁流动性的影响。通过对铸件凝固组织的观察，发现铸件流动不均匀。(3)钛铸件的流动性：研究了铸件截面厚度、浇注温度和脱氧等因素对铸件流动性的影响。强制流体流动下的计算机凝固模拟：在二维截面上模拟了流体流动下水的凝固过程，并与可视化实验进行了比较，结果令人满意。(5)定向凝固铅锡合金圆盘的变形：测量了单向凝固圆盘底部的屈曲变形。已凝固层中的热应力是变形的主要原因。(6)液滴法研究初凝层的变形：研究了各种纯金属和二元合金。纯金属的变形仅取决于凝固层中的热应力。合金在共晶成分附近出现了异常大的正或负变形。其原因要么是固溶体析出导致的热收缩，要么是热膨胀。

In response to the needs for castings of thinner section thickness, solidification behavior of molten metal in flowing fields was studied for promoting the basic understanding of the processes of cast surface formation.(1) Fluidity of aluminum alloys in thin sections : Fluidity of Al-Si-Cu alloy wa studied by means of the suction test method. Effects of section thickness, suction pressure, mold materials, surface treatment, pouring temperature and mold atmosphere were studied. Effects of surface tension were discussed.(2) Fluidity of cast iron : Effects of section thickness, pouring temperature, inoculation and suction pressure on the fluidity of cast iron were studied. By examining the solidification structure, non-uniformity due to flow was found.(3) Fluidity in Titanium castings : Effects of section thickness, pouring temperature and deoxidation were studied. An indirect indication was obtained on the possible effects of deoxidation on fluidity.(4) Computer simulation of solidification under forced fluid flow : Solidification of water under fluid flow was modeled in 2-dimensional section and compared with visualization experiments with a satisfactory agreement.(5) Deformation of unidirectionally solidified Pb-Sn alloy discs : Buckling deformation was measured on the bottom of unidirectionally solidified discs. Thermal stress in the already solidified layer was found to be the major cause of the deformation.(6) Deformation study of initial solidification layer by means of drop method : Various pure metals and binary alloys were studied. Deformation of pure metals was found to depend only on thermal stress in the solidified layer. Abnormally large positive or negative deformation was found with alloys near eutectic compositions. The cause was either thermal shrinkage or expansion due to precipitation in solid solution.