The effects of different forming temperatures and different heat treatment processes on squeezing casting bimetal track plate were investigated by numerical simulation.The results reveal that the track plate is first solidified ahead at the contact position of the steel skeleton and mould

which is also the stress concentration position.The shrinkage defects

such as porosity

may appear in the thick and large position of the final solidification.The steel and aluminum composite forming of the bimetal track plate can be realized by squeezing casting with absence of defects such as shrinkage and crack.The microstructure of the squeezing castings presents typically near spherical structure with the uniform and fine distribution.There exist some fine grain regions and mixed crystal areas at the interface of the steel and aluminum.The grain boundary of the alloy is smooth after heat treatment and the intergranular phase disappears.After heat treatment

the interface of steel and aluminum is separated slightly with about 2～6μm.The Brinell hardness of high strength aluminum alloy after first stage solid solution reaches 165 HB

and it reaches 180 HB after the two-stage solid solution treatment.