Magnesium alloy is the lightest structural metal with high recycle ability. Magnesium alloy is widely used for a casing and a cover of mobile electric equipment. Motor industries are also interested in magnesium alloys in order to reduce the weight of a car and which can leads low environmental pollution. Recently, new alloys have been actively developed to extend wide application of magnesium alloys especially for the structural use. Fatigue behavior is important on the reliability of structure. In case of magnesium alloy, data of fatigue property can be found from more than 50 years ago [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36] However, not all data can be able to use for the current design. For example, concerning on fatigue limit which is important on the design, some of the previous data shows the knee in the S-N curve like a steel material, but some of them don't show it like an aluminum alloy. One possibly reason of why this confusing occurred may be due to the testing conditions shown un-clearly in the report. Humidity affects on the fatigue characteristic of a magnesium alloy significantly, that will be discuss in the following part of the present paper. Another important aspect is that most of components made by magnesium alloy are produced by casting process and the casting material unavoidably includes pores. If fatigue cracks initiated from the inherent flaws, fatigue strength is dominated by the size, position and shape of the flaw. However, it does not mean intrinsic fatigue strength of the material. Material development has been significantly advanced in recent years. Therefore, it will be important to evaluate basic fatigue property of the advanced magnesium alloy based on a reasonable fatigue testing method.
In this paper, effects of humidity, surface roughness, manufacturing process and texture on fatigue behavior were shown to discuss and establish a reasonable fatigue test method of magnesium alloys.