Prediction of fracture onset in flashless warm forging Mg alloy AZ61

The paper presents an innovative precision forging process, highlighting the use of advanced simulation of net forging process in multiple-tool die set with consideration of counter-pressure and interaction of components so as to control tool speed and displacement of metal. In addition to the use of finite element method in optimization of process conditions, damage criteria have been formulated to investigate the effect on plasticity and tendency of formation of defects and define process conditions which contribute to cracking occurrence in warm forging of magnesium alloy AZ61. Both forged samples and numerical simulation prediction indicate minimization of cracking hazard in lower work-temperature range at relatively high strain rate by employing counter-pressure imposing hydrostatic component into state of stress.