液态模锻ZL205A铝铜合金热裂敏感性研究

Study on Hot Cracking Sensitivity of ZL205A Produced by Melted Metal Die Forging

铝铜合金的热裂敏感性较强,一般只能砂型铸造成形。文章利用螺旋线试样研究了液态模锻(MMDF)ZL205A的热裂敏感性。结果表明,提高液锻比压可以显著降低铝铜合金的热裂敏感性。当液态模锻压力超过一定水平时,可以完全根除热裂缺陷。液态模锻ZL205A的热裂机制服从液膜理论。包围初生固相的液膜发生二元共晶或三元共晶转变时,凝固收缩会导致液膜断裂。液锻的高比压可以使这种凝固收缩得以及时补偿,进而保持了液膜的完整性,根除了热裂缺陷。

Aluminum copper alloy is high sensitive to hot cracking and is considered to be formed only by sand casting.In this paper,the hot cracking sensitivity of ZL205A produced by the Melted Metal Die Forging(MMDF for short)process was studied by using spiral specimen.The results show that increasing the MMDF pressure can significantly reduce the hot cracking sensitivity of Al-Cu alloy.When the MMDF pressure exceeds a certain level,the hot crack defect can be completely eliminated.The hot cracking mechanism of MMDF ZL205A obeys the“liquid film theory”.When binary eutectic or ternary eutectic transition occurs in the liquid film surrounding the primary solid phase,the solidification shrinkage will lead to the fracture of the liquid film.The high MMDF pressure acted on the melted alloy can compensate the solidification shrinkage in time,thus maintaining the integrity of the liquid film and eliminating the hot crack defects.