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分别使用普通硅砂和铬铁矿砂浇注铝合金阶梯试样,分析其试棒的抗拉强度、屈服强度、伸长率以及硬度,分析其金相组织,测其晶粒度和二次枝晶间距并进行对比。试验表明,采用铬铁矿砂铸造,明显提高铸件的抗拉强度;伸长率在壁较薄处也有较大提升,而在壁厚较厚处则优势下降;晶粒细化效果显著,晶粒度和二次枝晶间距优于普通硅砂铸件,冷却速度敏感性小于普通硅砂铸件。因此铬铁矿砂更适合于作为强度要求高的铸件,但是由于其强烈的激冷效果使得金属液流动性变差,因此不适合做形状复杂铸件的造型材料,加之价格昂贵,其使用受到限制。
Respectively, using ordinary silica sand and chromite sand pouring aluminum alloy step sample, the test rod tensile strength, yield strength, elongation and hardness, analysis of the microstructure, measured the grain size and secondary dendrites Pitch and compare. Tests show that the use of chromite sand casting, significantly improve the tensile strength of the casting; Elongation at the wall is also thinner Department also has a greater increase in the thickness of the Department of the advantages of decline; significant grain refinement, crystal Grain size and secondary dendrite spacing is better than ordinary silica sand castings, the cooling rate sensitivity is less than ordinary silica sand castings. Therefore, chromite ore is more suitable as a high-strength castings, but because of its strong cooling effect makes the liquid metal mobility worse, it is not suitable for molding materials with complex shape, combined with expensive, its use is limited .