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本文采用自行改装设计的固液态力学性能测试装置对铸造Al—Cu合金在固液态时的强度和塑性进行了研究。考察了温度、钢含量、铸态晶粒形状、钛的孕育作用及低熔点杂质对合金在固液态时的强度和塑性的影响。研究结果表明,合金在固液态时由于液体在晶间的分布,呈现出一个明显热脆弱区,强度和塑性值都很低,是铸件形成热裂的主要原因。单向凝固获得的柱状晶,在固液态时的横向力学性能比普通柱状晶横向性能可以高出十倍。对合金进行孕育处理,减少晶界的低熔点杂质对提高固液态的力学性能,防止热裂纹产生具有重要的作用。
In this paper, the strength and plasticity of cast Al-Cu alloy in solid-liquid state were studied by the self-designed solid-liquid mechanical property testing device. The effects of temperature, steel content, as-cast grain shape, the inoculation of titanium and the low melting point impurities on the strength and ductility of the alloy in solid-liquid state were investigated. The results show that the alloy is in solid-liquid state due to the distribution of liquid in the intergranular, showing a clear hot fragile zone, the strength and plasticity values are low, the main reason for the formation of thermal cracking of the casting. Columnar crystals obtained by unidirectional solidification have lateral mechanical properties that are ten times higher than that of ordinary columnar crystals in the solid-liquid state. The alloy inoculation process to reduce the low melting point impurities in the grain boundary to improve the mechanical properties of solid-liquid state, to prevent the occurrence of hot cracks play an important role.