| It is well-knomn that metal materials may undergo ductile fracture(DF) and the loss of load-carring capacity, when plastic deformation reaches a certain limit. DF is an important factor that affects the formability and safety of engineering materials. The accurate prediction of DF plays a vital role in the design and optimization of the product process. In this process, the selection of a suitable and reliable fracture criterion is very necessary. From the present study, many of the ductile fracture criterion and ultimate fracture criterion is proposed for predicting the crack initiation location and time in the process of plastic deformation. As a green environmental protection and excellent comprehensive properties material, stainless steel has been widely used in various fields. In recent years, a lot of research have been done for the mechanical properties and corrosion, but the study on fracture criterion of stainless steel in the forming process is rarely mentioned. In this paper, 304 stainless steel as the object, studies the fracture criterion of the forming process, and the criterion is applied to the field of fine blanking, evaluation the fine blanking performance of 304 stainless steel.In this paper, 7 different cylindrical upsetting tests of 304 stainless were designed for the rupture experiments. The data was calculated which measured in the process of experiment, fracture criterion was established for 304 stainless steel in the process of deformation, namely the " average stress triaxiality-equivalent strain " criterion. The results show that, the average stress of three axis has a limit value-1/3.The cylindrical plate upsetting model of 304 stainless steel was established on the ABAQUS/Explicit platform, the criterion of fracture based on experiment was used in the finite element(FE) simulation. The various of stress and strain of the FE were extracted to establisht the fracture criterion by the method of curve fitting. The results show that the simulation for 4th calibration was able to meet the plate upsetting experimental phenomena.Compression experiments through the ring specimen of 3 different size were conducted, and the experimenf datd was used in the simulation of ring compression. The FE simulation and experiment results were compared to verify the applicability and reliability of the fracture criterion. The results show that the fracture criterion based on 4th calibration was better to predict the rupture samples of compression experiment.In order to study the fine blanking performance of 304 stainless steel, a experiment device of material fine blanking performance and a method of drawing performance were designed. 304 stainless steel's fracture criterion was used in the fine blanking simulation, to predict the cracks generated during punching. Through the measurement of fine blanking simulation results of l and t, according to the given standard, the fine blanking performance of 304 stainless steel was evaluated. The results show that, the fine blanking performance of 304 stainless steel was poor. |
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