Abstract
Weight reduction of car bodies is a serious environmental issue, since the large amount of carbon dioxide is generated by transportation equipments. Currently, aluminum alloys are expected to be used for a car body for weight reduction, and further weight reduction will be achieved, if magnesium alloys can be applied. But magnesium alloys have several practical disadvantages; lower strength, poor corrosion resistance, etc. It has been known that strength of metallic materials can be improved by grain refinement, and recent reports revealed severe plastic deformation like high pressure torsion (HPT) or friction stir process (FSP) is very effective to reduce grain size. In the present study, the effect of grain size on the strength in FSPed Mg-Al-Zn alloys is investigated. The conditions for FSP and subsequent heat treatment are changed to obtain the specimens with different grain size.
