Microstructural Studies and Mechanical Properties of Hydroforming Process of AZ31B Magnesium and AA 2024 Aluminum Alloys Sheets at Elevated Temperatures

Hydroforming is one of the newest sheet metal forming methods that has been widely considered in the industry in the last two decades. In the present research work, the sheet hydroforming process of 2024 aluminum and AZ31B magnesium light-alloys at elevated temperatures has been studied experimentally. In order to evaluate the quality of the produced specimens, the thickness strain created in the cups has been investigated. Then, the relationship between thickness strain distributions with the grain size was discussed using hardness test and microstructure images obtained from scanning electron microscopy (SEM). In order to confirm the gained numerical values, the repeatability of experimental results was performed. The outcomes demonstrated that the suitable temperatures for the hydroforming process of 2024 Al alloy and AZ31B Mg alloy respectively gained to be 250 °C and 200 °C. The maximum amount of elongation and plastic strain (due to simultaneous bending and stretching) occurred in the wall of the cup and despite the friction of contact between the sheet and the matrix in the flange region, the amount of strain in this area increased. According to the results of the current study, the maximum increase in hardness and decrease in grain size were obtained 37% and 20% for AA 2024 and 24% and 42% for AZ31B, respectively, in the wall area in comparison with the bottom of the product.