Wear damage of steam generator tubes of nuclear power plants can cause leakage of radioactive substances. So the evaluation of tubes' integrity is very important from the viewpoint of nuclear ecocide. In the present study, sliding wear behaviors of Inconel 600 and 690 steam generator tube materials mated with 409 stainless steel commonly used as the support plate were investigated at room temperature in an air environment. For more precise prediction of wear behaviors of steam generator tubes, Archard equation was modified, and the modified wear coefficients were estimated as a function of sliding distance. When using the modified Archard equation, the reliabilities for prediction of wear behavior of Inconel 600 and 690 mated with 409 stainless steel increased from 71.8% to 83.8% and from 60.2% to 85.2%, respectively.