Study Of Process Optimization And Microstructure Evolution In Radial Forging Process Of ?600mm Round Solid Billet

The radial forging is developed on the basis of the traditional free forging,it is a special pulling forging technology for round and tubular components.Radial forging technology has a very broad application prospects in ships,military industry,aerospace,rail transportation and other equipment manufacturing fields.According to the practical forging process of ?600mm round solid billets with SMX-p radial forging machine,there is serious defect of concave profile in end surface,which made a big waste of materials and energy sources.At present,there are few studies on the radial forging process and the microstructure evolution of large round billet forging.In this paper,based on thermo-coupled plastic forming finite element theory and microstructure evolution model of 42 CrMo steel.Coupled thermo-mechanical model and microstructure evolution model of 42 CrMo steel for the hot radial forging process were established based on the DEFORM-3D FEM software.Firstly,the complete process of radial forging was simulated according to the initial process,the forming process of the defect of concave profile in end surface was analyzed.It is confirmed that the first feed,the radial reduction of every pass and the friction factor are the main factors that affect the defect of the end face.Under the rated forging force the combination of the main process parameters is determined.Secondly,the influence of different feeding speed,radial reduction,and friction factor on forging penetration efficiency,axial stress,deformation uniformity were analyzed.During the radial forging of large round billet,the heart of the billet exist axial tensile stress all the time,So the different structure forms of anvil were studied in order to lower the axial tensile stress and the length of the tensile stress area.At last,the distribution of microstructure of the initial process was analyzed.The influence of first feed,feeding speed,radial reduction,and friction factor on the microstructure evolution was studied.Under the rated forging force the defect of concave profile in end surface,the penetration efficiency and deformation uniformity had been significantly improved,theaxial tensile stress of new process was reduced significantly.The microstructure evolution of radial forging was obtained.The obtained results provide some basis to design and optimization of process parameters,the predication and control of forging quality during radial forging process,especially for the product of large round billet in radial forging process.