Estimation methods for strain-life fatigue properties from hardness

Several methods for estimating fatigue properties from hardness are discussed, along with all existing estimation methods. The (direct) hardness method proposed by Roessle and Fatemi provides excellent estimation results for steels. So-called indirect hardness methods utilizing the ultimate tensile strength predicted from hardness were proposed in this study and successfully applied to estimate fatigue properties for aluminum alloys and titanium alloys. The medians method proposed by Maggiolaro and Castro is found to provide the best estimation results for aluminum alloys. Based on the results obtained, some guidelines are provided for estimating fatigue properties from simple tensile data or hardness. In addition, a new relationship of ultimate tensile strength versus hardness is proposed for titanium alloys.