Alumite treatment is one of typical surface treatments for aluminum alloy and it provides oxide layer (alumite) on the surface. The method has been widely used for aluminum alloy, because the alumite has some excellent characteristics such as wear resistance, electric resistance and so on. Thus, fatigue tests were carried out for specimens having two different alumite treatments and without the treatment by means of a dual-spindle rotating bending fatigue testing machine. Fracture surfaces of all the failed specimens were observed by using SEM, and the fatigue fracture mechanisms were discussed from a viewpoint of the fractography paying an attention to the effect of the alumite treatments.
