EFFECT OF ANISOTROPY OF MECHANICAL CHARACTERISTICS OF STEELS ON THE STRENGTH AND STRESS-STRAIN STATE OF LARGE-DIAMETER PIPES

摘要

In the oil and gas industries, thick-sheet steels are widely used for pipes and in welded components assuming the shape of shells of revolution and operating under internal pressure. The mechanical characteristics of structural materials, which are obtained from uniaxial-tension testing of specimens, are normally used to evaluate the bearing capacity of the components in question. It is known, however, that large-diameter pipes and shell structures operate more frequently in a biaxial stress state. Many sheet steels possess plastic anisotropy. It has been theoretically and experimentally established that the mechanical characteristics of carbon and low-alloy steels depend on the angle of cut θ of the specimen - the angle of incline of the specimen being cut to the direction of rolling. The angle θ exerts a significant influence on the character of the relationship between the stress σ_i and strain intensities ε_i. Correspondence between experimental and computed data for different metals, alloys, and articles subject to different treatment regimes has been found completely satisfactory.