The effect of temperature cycling on the physical properties of FS-1 magnesium alloy sheet metal

Abstract

An investigation was made of the effect of different cyclic heat treatments on the high rate creep and stress-strain characteristics of FS-lh magnesium alloy and 75S-T6 aluminum alloy sheet metal. The heat treatments to which the alloys were subjected consisted of a varying series of heating and cooling cycles such that the periods at heat treating temperature totaled 60 minutes. Temperatures investigated were 250[degrees] and 550[degrees]F. Following heat treatment, both tensile and creep tests were conducted at room temperature and at the temperature of heat treatment. This thesis encompasses the investigation of FS-lh magnesium alloy, while the investigation of 75S-T6 aluminum alloy is covered in the current thesis of the author's co-worker(1). It was found for the range of heat treatment cycling (1-20 cycles) and temperatures investigated, that there is no effect on the physical properties as a result of changing the number of heating cycles. Cyclic heat treatment at 550[degrees]F was the only treatment to result in a reduction of physical properties, and this only when tested at room temperature. It was also found that, within the time range investigated, exposure time exhibits a negligible effect on the physical properties of the material. However, elevated temperatures affect the yield and ultimate properties.