Investigation on Forming Defects During Thixo‐forging of Aluminum Alloy AlSi7Mg

The appearance of pores and segregation between solid/liquid phases during semi‐solid forming has been a long‐term challenge for the large scale utilization of semi‐solid forming in industry. Both phenomena can be influenced by velocity, temperature and pressure. In this study a flat flange and an angled flange were used in investigating the metal flow behavior during thixo‐forging of aluminum parts. Evaluations of the thixo‐forged parts were performed with x‐ray inspection, microstructure and segregation analysis. The experimental results show significant tendencies between the types of the flange and the forming defects of pores and segregationThe results of numerical simulations showed that the hydrostatic stress was the main reason for the appearance of pores. The x‐ray inspections revealed that the appearance of pores and segregation during thixo‐forging could be avoided or alleviated by optimized die design.