Fatigue Properties of Inclined Cruciform Welded Joints With Artificial Pits

Abstract

Experimental and numerical investigations on the fatigue properties of inclined corroded cr uciform joints were conducted in this paper. Two artificial hemispherical notches were used to simulate pitting corrosion damage. Fatigue tests were carried out under uniaxial tensile cyclic loading. The fatigue S-N curves considering different types of corrosion damage were fitted by regression analysis. A relative hot spot stress concentration factor (HSSCF) concept was proposed. The influence of the pit size on the relative HSSCF of the cruciform joints was analyzed based on a numerical analysis. The fatigue notch factor (FNF), which considered the effect of corrosion pits, was used to describe the fatigue strength reduction. The FNF method and the Theory of Critical Distances (TCD) were employed to predict the fatigue life of corroded cruciform joints. It is concluded that pitting corrosion damage reduces the fatigue strength, but specimens without and with smaller corrosion pits exhibited similar fatigue strengths at 2 million cycles. The pit depth and radius are the main parameters affecting the relative HSSCFs, and an equation as a function of the pit depth and radius is obtained. The predicted S-N equations correlate well with the experimental results. The maximu m error of the fatigue life calculation results based on these two methods is only-27.8%. They can be used to predict the fatigue life of corroded cruciform joints.