半固态挤压铸造A319铝合金的固溶处理特性

Characteristics of Solution Treatment Semi-solid Squeeze Casting A319 Alloy

研究了固溶处理工艺对半固态挤压铸造A319铝合金硬度和显微组织的影响,探讨了半固态挤压铸造A319铝合金固溶处理的特性。结果表明,半固态挤压铸造A319铝合金与金属型重力铸造A319铝合金相比,其偏析小,凝固速率高,Al2Cu相更多地以共晶状存在于晶界处,Q-Al5Cu2Mg8Si6相则以共晶状、细条状存在于晶界处;后者偏析较为严重,凝固速率较低,Al2Cu相更多地以块状或混合状存在于晶界和基体中,Q相多以紧密的块状、短棒状存在于晶界和基体中。含Cu相的形状影响其在固溶处理过程中的溶解。半固态挤压铸造A319铝合金中的含Cu相比金属型重力铸造A319铝合金中的含Cu相更易溶解,所需的固溶时间更短,固溶处理有其优越性。505℃×3h的固溶处理工艺对半固态挤压铸造A319铝合金来说是合适的。

Effects of solution treatment on hardness and microstructure of semi-solid squeeze casting A319 alloy were investigated.The characteristics of solution treatment semi-solid squeeze casting A319 alloy was analyzed.The results show that compared with metallic mold casting A319 alloy,semi-solid squeezing casting A319 alloy exhibits the features of low segregation degree and high solidification rate,where eutectic Al2 Cu phase is distributed along the grain boundary,and Q-Al5Cu2Mg8Si6 phase in form of eutectic and fine strip is distributed in grain boundary.The metallic mold casting A319 alloy exhibits serious segregation and low solidification rate,where Al2 Cu phase exists in the grain boundary and the matrix in form of block or mixed structure,and Q-Al5Cu2Mg8Si6 occurs in the grain boundary and matrix in form of dense block and rod.The morphology of phase contained Cu is inhibited in solid solution process.The phase contained Cu is more easily solved,so it needs a short solid solution time,exhibiting the solid solution features.It is feasible for semi-solid squeezing casting A319 alloy with solid solution at505 ℃for 3h.