Microstructure characterization and tensile properties of squeeze-cast AlSiMg alloys

A research program was conducted to study the effects of squeeze pressure (70, 100 and 160 MPa) and heat treatment T6 on the structure, hardness and tensile properties of cast Al6Si0.3Mg alloys. The influence of squeeze pressure on macro- and microstructures of Al6Si0.3Mg alloys has been investigated. Some of castings were solution treated at 540 °C for various times and others were subjected to aging at 170 °C after solution treatment. The results indicated that precipitation occurred within about 30 min for both cast and squeeze cast alloys. The hardness began to increase and maximum values were observed after about 10 h for as-cast alloy. Increasing of squeeze pressure (70-160 MPa) accelerated strength of the alloys from 8 to 4 h, respectively. Squeeze pressures decreased the percentage of porosity and increased the density, also it decreased the grain size of α-Al and modified the Si eutectic. Hardness and tensile properties increased with both heat treatment and increasing of squeeze pressure.