Effect of Squeeze Casting Parameters on Microstructure and Mechanical Properties of AlSi9Mg Alloy for Automobiles
AlSi9Mg alloy is a common squeeze cast aluminum alloy that is widely used in the automotive industry.The squeeze casting tests of AlSi9Mg alloy under three different extrusion pressures of 10 MPa,30 MPa and 50 MPa were carried out,and it was compared with the traditional gravity casting.The effects of squeeze casting pressure on the microstructure and mechanical properties of the alloy were investigated.The results show that the microstructure of AlSi9Mg alloy changes significantly with the increase of extrusion pressure.The secondary dendrite arm spacing of the squeeze casting specimen is significantly reduced from 10.1 μm at 10 MPa to 4.2 μm at 50 MPa,while that of the gravity casting specimen is bigger,which is 13.8 μm.At the same time,the grains are refined,and the structure is more homogeneous and denser.With the increase of the extrusion pressure,the porosity of the specimen is significantly reduced,and the density is gradually increased,indicating that the extrusion casting process can effectively reduce the casting defects and improve the density of the castings.The squeeze casting can significantly improve the tensile strength and elongation of AlSi9Mg alloy.Under the extrusion pressure of 50 MPa,the tensile strength of the specimen reaches 234.3 MPa,which is nearly 40％higher than that of the gravity casting specimen,and the elongation is also increased from 1.1％of gravity casting to 2.4％.
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