Casting Defects Influence On Low Pressure Casting Aluminum Alloy Wheel Mechanical Properties

Based on mechanical properties test results analysis to the aluminum alloy wheels,there are only two main kinds of defect influence on low pressure casting aluminum alloy wheel mechanical property.One is oxide inclusion-Bifilm formed during the filling process;and another is shrinkage porosity and eutectic segregation formed during the solidification process.Bifilm oxide inclusion is easy to appear on the wheel with vortex spoke design.Because the size of bifilms observed on the specimen fracture is very small,it mainly impacts the specimen elongation result,and very low influence on tensile strength and yield strength.Reducing the oxide inclusion defects formed during filling process is mainly through the reduction of pressure increasing speed in filling phase.The shrinkage porosity defects occurred mainly on the hub and spoke of the wheel.Because the size of shrinkage porosity defect observed on the specimen fracture is very small,it mainly impacts the specimen elongation value,and low influence on yield strength and tensile strength of the specimen.To reduce or eliminate shrinkage porosity defects,is mainly by adjusting the cooling parameters of the mould,make the aluminum alloy liquid completely solidified in accordance with the principles of progressive solidification.Eutectic segregation occurred mainly on the spoke near the outer horn of the wheel.When the specimen appears a large area of eutectic segregation,it will not only cause elongation of the specimen decline significantly,but also make yield strength and tensile strength lower than the hub's strength,this is not in line with the trend of mechanical properties increasing from hub to outer horn on the wheel.Through optimising the cooling parameters of the segregation region on the mould can eliminate eutectic segregation defect.