Prolonged fatigue life in aluminum clad steel by electropulsing treatment: Retardation of interface-microcrack formation

The prolonged fatigue life of aluminum clad steel (Al clad steel, ACS) using electropulsing treatment is systematically investigated by characterizing the microstructural change at different fatigue cycles. The microstructural changes associated with fatigue damage evolution show that cracks are prone to initiate at Al grains of the interface and propagate toward the Al side in the fatigue test due to a preferred accumulation of geometrically necessary dislocations (GNDs) in the soft Al grains near the interface. The electropulsing treatment with a subsecond duration is proved to be efficient in healing the fatigue damage and significantly prolonging the fatigue life of the ACS. The increased fatigue life by electropulsing treatment is attributed to the diminished density of piled GNDs and the retardation of microcrack formation at the interface. The present study elucidates the failure mechanism of ACS and proves that electropulsing treatment is an efficient method to prolong the fatigue life of laminated metal composites by healing the accumulated damage during the fatigue test.