Crushing and diffusion welding are two critical healing stages of interior void defects in heavy forgings.The healing result depends on many factors during the forging process,such as stress,temperature,deformation an...Crushing and diffusion welding are two critical healing stages of interior void defects in heavy forgings.The healing result depends on many factors during the forging process,such as stress,temperature,deformation and type of material,while the void diffusion welding condition is still not well known at the present.This paper is concerned with the deformation welding condition of the closed void interface in heavy ingot during the hot forging process.A void crushing experiment is carried out to recognize the microstructure of the closed void interface.According to the healing mechanism at high temperature,a new physical simulation model is setup to study the deformation welding process of the closed void interface based on the theory of atom diffusion and the interface contact mechanics prototype.Compared with the experimental results,the influence of deformation degree,forming temperature and holding time on the welding quality is discussed,and then the deformation welding condition of closed void interface is presented.The proposed condition helps to improve forging technology and product quality.展开更多
In this paper,a kind of mathematic method for optimizing stretching process of large forgings is proposed.Distributions of effective strain within forged ingots is described by a Gauss function,which is obtained from ...In this paper,a kind of mathematic method for optimizing stretching process of large forgings is proposed.Distributions of effective strain within forged ingots is described by a Gauss function,which is obtained from the simulation of flat-anvil stretching process.Successive stretching is expressed by the superimposing Gauss functions.Optimized stretching process,with both homogeneous and certain strain in the center of forgings,is presented by derivation of this function.The relationship between effective strain and the values of feed is obtained during the successive stretching with a rotation angle of 90° and a feed displacement of 1/2 anvil width.The optimization result is verified by finite element simulation.Optimized value of feed obtained using this method can ensure both uniformity and forging penetration.It provides mathematic model and theoretic basis of optimizing large forging stretching process.展开更多
基金the National Natural Science Foundation of China (Nos.50435010 and 51005197)the National Scientific and Technical Supporting Programs of China (No.2007BAF02B12)the Doctor Fund Project of Yanshan University (No.B298)
文摘Crushing and diffusion welding are two critical healing stages of interior void defects in heavy forgings.The healing result depends on many factors during the forging process,such as stress,temperature,deformation and type of material,while the void diffusion welding condition is still not well known at the present.This paper is concerned with the deformation welding condition of the closed void interface in heavy ingot during the hot forging process.A void crushing experiment is carried out to recognize the microstructure of the closed void interface.According to the healing mechanism at high temperature,a new physical simulation model is setup to study the deformation welding process of the closed void interface based on the theory of atom diffusion and the interface contact mechanics prototype.Compared with the experimental results,the influence of deformation degree,forming temperature and holding time on the welding quality is discussed,and then the deformation welding condition of closed void interface is presented.The proposed condition helps to improve forging technology and product quality.
基金the National Science Support Project found by the Ministry of Science and Technology of China (No.2007BAE51B04)
文摘In this paper,a kind of mathematic method for optimizing stretching process of large forgings is proposed.Distributions of effective strain within forged ingots is described by a Gauss function,which is obtained from the simulation of flat-anvil stretching process.Successive stretching is expressed by the superimposing Gauss functions.Optimized stretching process,with both homogeneous and certain strain in the center of forgings,is presented by derivation of this function.The relationship between effective strain and the values of feed is obtained during the successive stretching with a rotation angle of 90° and a feed displacement of 1/2 anvil width.The optimization result is verified by finite element simulation.Optimized value of feed obtained using this method can ensure both uniformity and forging penetration.It provides mathematic model and theoretic basis of optimizing large forging stretching process.
