The Numerical Simulation And Defects Evaluation Of Heavy Forgings During Upsetting Process

Heavy forgings in high quality are demanded for manufacturing of heavy machines that deeply influences the national economy and defense security. Heavy forgings are forged from steel ingots in that there are some defects such as segregation, porosity, micro-cracks inevitably, and the heavier steel ingot is, the more serious defects are. As a basic forging technique, upsetting can eliminate void defects so that the mechanical performance of materials will be greatly improved. But un-appropriate upsetting process will result in crack defects at the center and surface of ingots, so to forecast these defects has great significance to guarantee the quality of forgings.The process of upsetting is simulated with finite element software MSC.MARC in this paper. Firstly, the coupled thermal-structural field numerical simulation of upsetting of cylinder ingot between two flat platens was implemented, the internal stress, strain and temperature distributions were obtained. through the analysis of the relationship between central point stress and down ratio, the critical height width ratio (H/D) was given. During the analysis process, the Oyane formula was used to simulate the evolvement of defects, the law of defects evolvement was obtained.Secondly, through the simulation of upsetting of a cylinder ingot with cone-shaped dies, the distribution of stress and strain was obtained. It was convinced that this process can get the hard deforming zone worked adequately, therefore the material performance of zone can be improved. It was shown after the second working, the internal strain appears symmetrical.This research is important to the improvement of upsetting process.