Weight reduction is a hot topic in automotive industry. Both the applications of tube hydroforming technique and magnesium alloys offer a large potential for reducing the weight of automotive components. In this research, the relationship between forming pressure and bulge height, the maximum forming pressure and the forming limit during the tube hydraulic bulging process are first analysed. A self-designed warm hydraulic bulge forming equipment and the seamlessly extruted magnesium alloy AZ61 tubes, are used for carrying out a series of warm hydraulic bulge tests, and discussing the formalibility of the magnesium tubes at various temperatures. Furthermore, the flow stress curves are determined by the mathematical model in this paper with the bulge forming test results. Then the validity of the analytical model is verified by comparing the forming pressure and bulge height between analytical and experimental values.

Magnesium alloy tubes have good formability at elevated temperatures. In this study, a finite element code DEFORM 3D is used to simulate the result of T-shape hydroforming at working temperatures 150¢J and 250¢J with magnesium alloy AZ61 tubes and then conducts the hydroforming experiments. By modifying the loading paths, products with uniform thickness and branch height are obtained 49mm. The results of simulation are compared with the experimental results to verify the validity of this modeling. On the other hand, the effects of the die fillet radius on tube formability during y-shape hydroforming are discussed. With the right die fillet radius r1¡×10mm and the left die fillet radius r2¡×30mm, a better formability of the tube is obtained.

This master’s thesis is dealing with low-fatigue behavior of magnesium alloy AZ61, prepared via squeeze casting method. The main aim of this work was to obtain the basic mechanical properties as well as the low cycle fatigue data. Additional metallographical evaluation of microstructure and fractographical analysis after fatigue tests was made.

Microstructure and mechanical properties of AZ61 magnesium alloy in cast condition and after solution annealing were compared. The compare of mechanical properties of alloy, their hardness and microanalysis of occurring phases are included in this work. For compare has been used a light microscopy, tensile test, hardness measurements and scanning electron microscopy.