Abstract
Plain fatigue and fretting fatigue tests of dies steel SKD61 with radical nitriding and ion nitriding were carried out. Plain fatigue strengths of the specimen with both nitridings were slightly higher than that of the specimen without nitriding. On the other hand, fretting fatigue strengths of the specimen with nitriding were significantly high compared to that of the specimen without nitriding. Fretting fatigue limits of the specimen without nitriding, with ion nitriding and with radical nitriding were around 200MPa, 350MPa and 400MPa, respectively. The low tangential force coefficient and high hardness of the specimen with radical nitriding will be the main reasons for excellent fretting fatigue resistance.
