Compound forging is a promising approach for the manufacturing of bimetal parts. However, reliable material interlock is difficult to be obtained in compound forged bimetal parts due to the asynchronous material flow. To overcome this problem, in this work, the previous proposed thixotropic-core compound forging (TCF¹) method was applied in the precision forming of a bimetal cylinder spur gear. This investigation focuses on the feasibility of this new forming method. An aluminum alloy core and a steel shell were used as raw materials. The effects of the aluminum alloy core billet status on the material interlock and the shell thickness distribution were studied. Moreover, the microstructures and mechanical properties of the aluminum alloy core in the bimetal gear were investigated. The results suggested that the synchronous material flow could be achieved in the TCF. On this basis, reliable material interlock was obtained. Moreover, the thixotropic core is helpful to improve the uniformity of the shell thickness distribution by diminishing the friction. The liquid segregation in the thixotropic core can be remarkably diminished by the three-dimensional compressive pressures provided by the outer shell during the synchronous material flow. Therefore, uniform microstructure and property uniformities can be obtained in the core of bimetal parts manufactured by TCF. Furthermore, thixotropic core billets with a liquid fraction (f_l) lower than the requirements of conventional thixoforming were found to be viable in TCF.

复合锻造是制造双金属零件的一种很有前途的方法。然而，由于材料流动不同步，复合锻造双金属零件难以获得可靠的材料互锁。为了克服这个问题，在这项工作中，先前提出的触变芯复合锻造（TCF ¹) 方法应用于双金属圆柱直齿轮的精密成形。本次调查的重点是这种新成型方法的可行性。以铝合金芯和钢壳为原材料。研究了铝合金芯坯状态对材料互锁和壳厚分布的影响。此外，研究了双金属齿轮中铝合金芯的显微组织和机械性能。结果表明，在 TCF 中可以实现同步材料流动。在此基础上，获得了可靠的材料联锁。此外，触变核有助于通过减少摩擦来提高壳厚度分布的均匀性。在同步材料流动过程中，外壳提供的三维压缩压力可以显着减少触变核中的液体偏析。因此，TCF 制造的双金属零件的芯部可以获得均匀的微观结构和性能均匀性。此外，具有液体部分的触变芯坯（f _l ) 低于传统触变成形的要求被发现在 TCF 中是可行的。