A thixotropic-core compound forging technology was proposed for forming an aluminum-steel bimetal standard cylinder spur gear. The effects of initial temperature and thickness of the steel shell on bimetal synchronous deformation mechanism of the gear were investigated by finite element method（FEM）. The results indicate that the synchronous deformation behavior of the billets is determined by the ratio of thickness to radius of the steel shell. During the forming process

reliable mechanical interlock is formed between the aluminum alloy core and steel shell. In the bimetal gear

the thickness at the tooth tips of steel layer is increased and that at tooth roots is decreased

thus forming cracking dangerous zone. It is helpful to improve the fluidity of steel shell with increasing steel shell temperature. However

the aluminum core suffers anoverly heating when contacting steel layer at higher temperature

leading to the sharply decrease of the flow stress and disorders. When the initial thickness and temperature of steel shell were 4 mm and 1 100 ℃

respectively

the synchronous deformation quality is desirable. In conclusion

the forming dies were designed and the experiment was carried out based on the simulated analysis. A well-formed bimetal gear was obtained

demonstrating that the thixotropic-core compound forging technology was a satisfactory method for producing complex aluminum-steel bimetal components.