Effect of deformation and heat treatment on fabrication of large sized ring by mandrel forging of hollow ingot

摘要

Mandrel forging is a relatively simple process but needs multiple forging steps. A pierced blank isnused as a preform for the conventional ring forging process and manufactured from solid ingot bynseveral open die forging steps, such as cogging, upsetting and piercing. Since conventional ringnforging process is a very complicated manufacturing process, it is not so efficient and cost-neffective process. In this study, ring forging process is developed using a hollow ingot as anpreform. When a hollow ingot is used, open die forging steps to manufacture a pierced blank arennot necessary. Hollow ingot has been directly forged into the ring by mandrel forging. Designnvariables for the new process are mainly related to characteristics of final forged ring productnsuch as ingot size, forging amount and rotation speed. However, these variables are significantlynaffected by one parameter, that is, deformation amount by which the deformation energy,nmicrostructure and mechanical properties of forged ring are determined. Therefore, mechanicalnproperties with respect to the deformation amount are investigated by hot forging test of anstaircase model. Process parameters of cast ingot and mandrel forging are studied on thencondition that deformation amount of forged shell at each position can be reached to somenvalues.