Investigations of Fatigue Performance of S135 Drill Pipe Steel under Uniaxial Loading

摘要

The fatigue life of S135 drill pipe steel was investigated by means of tension-compression loading and torsion loading under uniaxial loading during the fatigue test. The quantitative formulas of fatigue life were obtained by regression analysis method, and the fatigue fracture mechanism was analyzed. The results show that a linear correlation was found between fatigue life and effective stress in the double logarithmic plots. Cracks initiated from the specimens surfaces under tension-compression loading as well as torsion loading. For the tension-compression fatigue and the torsion fatigue specimens, the main characteristics for cracks propagation were striations and sheares ripple marks, respectively.