High cycle fatigue behavior of the forged Mg–7Gd–5Y–1Nd–0.5Zr alloy

Abstract

This paper investigated the high cycle fatigue behavior of a forged Mg–7Gd–5Y–1Nd–0.5Zr alloy with different stress concentration factor (Kt), under different stress ratio (R), and along different loading direction. The smooth specimen (Kt = 1), under R = 0.1 and along longitude direction, shows a high fatigue strength of 162 MPa at 107 cycles. The fatigue behavior of the forged Mg–7Gd–5Y–1Nd–0.5Zr alloy exhibits a high sensitive to the notch. Moreover, change of stress ratio from 0.1 to −1 may also result in a bad fatigue property. The flux inclusions were elongated along longitude direction and/or transverse direction during the forging process of the Mg–7Gd–5Y–1Nd–0.5Zr alloy. The interface between the flux inclusion and the matrix may debond and serve as the crack initiation site during the fatigue loading process, leading to the deterioration of the fatigue property along thickness direction and a high anisotropic fatigue behavior between longitude direction and thickness direction.

Keywords

• Magnesium alloy
• Forge
• High cycle fatigue
• Stress ratio
• Inclusion