Experimental and Numerical Determination of Fracture Toughness of Oil Pipelines in St 37 Group

Measuring the value of fracture toughness KIC as the crack initiation criteria (in first mode of stress in PSN state) to stretch FAD curves for oil pipelines strengthen steels plays a very important role. In this research CT test has been done on six standard samples to calculate the fracture toughness of St 37 steel for oil pipelines. From obtained results, the value of fracture toughness equals to 143.3 MPa√m. Hence, finite element solution of the CT samples was done in Gerson theory. From the finite element design, the critical magnitude of crack opening at its tip (δ) was calculated. From this design by using LEFM (Linear Elastic Fracture Mechanics) formulas, the corresponded value of δ obtained about 138MPa√m. The comparison of two obtained results shows a good agreement between experimental and numerical results in atmosphere ambient.

Keywords:

Fracture toughness , oil pipeline , ductile crack propagation , Gerson theory , CT test