Effect of loading sequence on fatigue crack retardation of misaligned laser welded T-joints

Abstract This paper investigates the effect of overload and misalignment on crack propagation of laser welded T-joints. The results showed that the crack growth rates of these joints are like those of base material. For single overload, the increase of Δ K from 8.5 to 13 M P a m 1 / 2 multiplied the average retarded crack growth rate by 7.5 for R = 0.4. The highest crack retardation was caused by multiple overloads with overload ratio of 2 and interval of 10,000 cycles between overload peaks. According to fractographies, the size of plastic zone ahead of the crack tip and the crack branching governed for crack retardation.