The Research On Preforming Process For Large Ring

Some key components of heavy machinery, power generation equipment, petrochemical industry, shipbuilding and other industries are constituted of large rings. In the production of large rings blanks has a decisive role in the subsequent rolling,and blanks of large rings are made by ingots.Defects such as uneven chemical composition, organization and texture distribution, shrinkage, porosity, segregation and inclusions, because of uneven internal cooling and solidification process, usually exist in large ingots. The ingots should be deformed to constrain those defects. The traditional preforming process are prone to uneven deformation,poor appearance and other defects,which may lead to large rings scrapped.In this paper, upsetting process of large42CrMo ingot and upsetting and stretching process of304L stainless steel have been investigated based on finite element software,which provide guidance for preforming process of large rings.For upsetting process of large42CrMo ingots:Thermal-mechanical coupling model of two-stage upsetting processes and three-stage upsetting processes are established.By simulation the effect of conical structure anvil parameters(L, the cone angle) and deformation, drum coefficient are revealed.Furthermore, the law of equivalent strain distribution,metal flow,stress and load are investigated.Compared with the flat anvil upsetting process, it is found that upsetting process with conical structure anvil can make blank more uniform deformation,smaller drum coefficient and better internal stress state.For upsetting and stretching process of304L stainless steel:Through the analysis of coarse-grain in the304L stainless steel ring, upsetting and stretching process of304L stainless steel is proposed to improve the performance of the ingot.The process is simulated by finite element software,and according to the simulation results specific steps is worked out. Finally, rolling production is carried out to obtain fine-grain ring.