Warm Hydroforming of Sheet Metal Parts Made from Magnesium Alloys

  • Steffensen, Mikkel, (Project Participant)
  • Danckert, Joachim, (Project Participant)

    Description

    Weight reduction is a key issue in the automotive industry; in order to reduce weight new processing technologies e.g. hydroforming and laser welding for the manufacturing of tailored blanks and new materials e.g. high strength steel, aluminum, fiber reinforced plastics and magnesium are being introduced. In recent years much research has been carried out regarding the use of magnesium. This because magnesium alloys have a very low density (1.74 g/cm3) and have very good mechanical properties, especially if the mechanical properties e.g. yield strength and fracture toughness are related to the density. Up till now magnesium parts have mainly been processed by casting, a process which enables the manufacturing of complex geometries. However, the mechanical properties of the cast part may not meet requirements concerning mechanical properties due to porosities and there is also a limit to how thin a part can be made, e.g. a body panel in an automobile cannot be made by casting. Widespread use of sheet metal forming processes for the processing of magnesium alloys has up till now been very limited due to an insufficient knowledge about the forming technologies and suitable process parameters and due to that magnesium only very recently has become available as a fine grained sheet metal without pores and with advantageous mechanical properties.The forming of sheet metal parts made from magnesium alloys is inherently much more difficult than the forming of e.g. sheet steel. The main reasons for this are• magnesium alloys show very little formability at room temperature partly due to the hexagonal crystal structure. In order to obtain sufficient formability the forming has to be carried out at an elevated temperature • the strain rate has to be controlled very accurately; exceeding a critical strain rate causes fracture.Hydroforming is judged to be a very promising family of forming processes for the forming of complex sheet metal parts made from magnesium alloys; this because the liquid, which is in contact with the sheet during forming, makes it possible to control and maintain the magnesium sheet at a high and constant temperature during the forming and because the normal virtues of hydroforming, e.g. high drawing ration and the net shape or near net shape forming of complex geometries, can be utilized. The research will hopefully pave the way for an industrial utilization of magnesium sheet metal. In this connection it should be mentioned that the forming of magnesium sheet is not only of high interest to the automobile industry for the manufacturing of body panel parts, but sheet metal parts made from magnesium have also a high potential in the electronic industry e.g. in casings used for mobile electronic devices such as music players, phone and cameras (as a casing material magnesium has very favourable damping properties and high dent resistance).The purpose of the project is through fundamental research to establish knowledge which will pave the way for an industrial utilization of hydroforming processes to form complex sheet metal parts made from magnesium alloys. The research will encompass • the development of experimental equipment enabling experimental investigations of the warm hydroforming of parts made from magnesium alloyed sheet metal.• the development of methods enabling the determination of material and friction parameters required to carry out FEM-simulations reliably and to establish know how regarding simulation and optimization of warm hydroforming processes• experimental and theoretical investigation of the warm hydroforming of some typical shapes with the purpose of establish know how regarding how the warm hydroforming of magnesium can be carried out and to establish knowledge regarding process possibilities and limitations.The project, which was initiated ultimo 2004, has obtained financial support from STVF (1.7 MKr)(Mikkel Steffensen, Joachim Danckert, Department of Production, AAU)
    StatusFinished
    Effective start/end date31/12/200731/12/2007