Finite Element Simulation Op Internal Void Closure in Open-Die Press Forging

Abstract

In the manufacturing of heavy forgings, one of the most important aspects of the process is the consolidation of internal voids which result from the ingotmaking process. To insure a good quality finished product. these voids must be closed by proper choice of forging practices -including such factors as die geometry, amount of reduction, reduction speed. and workpiece temperature. This paper focuses on the first two of these factors and reports the results of a study on the effects of die width and reduction on the closing of a void.The deformation state in the cross-section of an ingot is predicted using a two-dimensional elastic-plastic finite element code for large strain, large deformation analysis. Simulations of forging with no void present are reported and compared with results from plasticine experiments. The effects of die width and amount of reduction on the internal deformation state are· examined. A single internal void is then modeled in the same geometry ingot as a smooth cavity at the ingot center. The nature of the void distortion and closure is predicted by the finite element model. NOMENCLATURE coordinates of current yield surface center ingot diameter deviatoric strain rate 501

Split Ends and Cracking Problem During Hot Rolling of Continuously Cast Steel Billets

“…As per [12], the effective strain was a better indicator of void closure than the hydrostatic stress. Shah et al [13] showed that voids could be closed by proper choice of forging practices including such factors such as die geometry, amount of reduction, reduction speed, and workpiece temperature. Kiuchi and Hsiang [14] discussed analytically the behavior of internal porosity in a plate rolling process using the method of limit analysis.…”

Simulação Numérica Aplicada Ao Estudo Da Relação Entre Largura De Contato Da Matriz E O Alongamento No Forjamento Em Matriz Aberta

“…Shah [7] e Wolske [8] Spur [9], analisou a mudança do avanço da ferramenta, alterando de uma mordida inicial com grande superfície de contato entre a ferramenta e a peça, Figura 4, em A, para mordidas posteriores mais curtas em B da figura 4. A segunda seção da peça, junto ao ponto central do eixo X, evidencia a falta de deformação no núcleo da peça (cor cinza escuro).…”

Finite Element Simulation of Pore Closing During Cylinder Upsetting

“…In spite of its significance, the related research works are not sufficient enough to be a guide for process design engineers. The reason lies in that both experimental approaches [1][2][3][4] and analytical or numerical approaches [5][6][7][8][9][10][11][12][13][14] have their own limitations. That is, experiments of large-scaled materials are very costly and difficult and most conventional simulation techniques are also poor at describing the pore closing phenomena due to their poor remeshing capability.…”

“…Stahlberg et al 6 studied rectangular cavity closing by the upper-bound method and they compared the predictions with experiments. From the late 1980s, finite element methods [7][8][9][10][11][12][13][14] have been used to study the pore closing phenomena in open die forging. Shah et al 7 applied threedimensional rigid-plastic finite element method to simulating open die forging processes without considering the pore closing phenomena.…”