Improvement in fatigue performance of thin fasteners via electromagnetic strengthening process

The fatigue behaviors of 1.5 mm-thick 2A12-T4 aluminum alloy fasteners processed by the electromagnetic cold expansion (EMCE) method are studied. The fatigue life of the fasteners processed by the EMCE method is 1.77 times that of the conventional direct mandrel cold expansion method at the maximum applied stress of 120 MPa. Finite element simulation shows that the EMCE process can introduce tensile stress in both hoop and radial directions, which avoids warping in thin fasteners. Moreover, the EMCE process achieves uniformly distributed compressive residual stress along the thickness direction, which is also beneficial to the fatigue improvement of the fasteners.