Research On Part Hot Gas Forming Process Of AZ31Magnesium Bellow

The current trends in the automotive, aircraft and space industries focus firstand foremost on a reduction of the vehicle weight and saving energy, therebyprotecting the environment. Owing to a number of their advantageous mechanicalproperties including, first of all, low density, magnesium alloys are more and morefrequently used as an engineering material. Hot forming of magnesium alloy hasbeen becoming one of the current hotspots. As a lightweight structural parts, thereis a wide range of needs for magnesium alloy bellows in the future.In this paper, high temperature tensile behavior of AZ31Mg alloy tube wasinvestigated. The influence of temperature and strain rate on the mechanicalproperties was studied. Based on the tensile test, flow stress constitutive equationwas fitted as hyperbolic sine shaped. On the use of DEFORM-2D, with thisequation, numerical simulation of forming process of Mg bellows was carried on.The influence of temperature and pressure on forming time and the thicknessdistribution was studied. Different stress and strain states helped to explaindifferent positions of the wall thickness mechanically.With the guidance of simulation, Mg bellows forming process was studied onhot gas pressure forming system which was developed by Harbin institute oftechnology. The influence of process parameters on forming time and the wallthickness was analyzed. Then the most reasonable forming process areobtained—623K,14MPa. Long axis bellows were formed by axis anisothermalgas-process forming with a small mold. It shows that simulation has a very goodprecision contrast with experiments.The microstructure of bellows at different temperatures were analyzed, thetransformation process was obtained. It shows that proper forming temperature wasbetween623K to673K. THE microstructure of bellows forming in the propertemperature range was fully dynamic recrystallization microstructure.