Abstract: The researching status on healing condition of internal defect of large forgings are introduced. To counter the characteristics that the size of voids are much less than that of ingots. According to St.venant‘s principle, the shape of voids is supposed to be ellipse shape which is dealt with easily in mathematics methods. Because the forge of large forges is done at high temperature, materials have character of viscosity flow. On the base of above-mentioned reasonable hypothesis, for linear viscous materials, the mechanics relation of fever stress and internal voids of object are made use of, which appears in the damage mechanics, the analytical equation which shows the relation of loads and void’s deformation is obtained, and then the healing mechanics condition of large forgings internal void defects is gotten. It indicates that stress state affects the close ways of voids and three-dimensional compressive stress state is the best one for healing the internal voids of object. This condition makes it possible straight to calculate deformation of voids by using the loads and reduction which are shown in hydraulic press, the healing condition of internal defect become more practicable. The discussions about different boundary stress and experiments show that the calculating results is agreeable with results of experiments.

Key words: Forge, Healing condition of defect, Large forgings, Material processing, Plastic deformation