Abstract
Mechanical properties, residual stresses and dimensional accuracies of large-size structural steel tubes of circular hollow section designated as STK400 and STKN490B were investigated. The sample number was 18 as delivered, and half cuts of them were normalized. As-delivered tubes exhibited higher yield strength, tensile strength and yield ratio, but less uniform elongation than their correspondent normalized ones. Charpy absorbed energy of as-delivered was smaller in circumferential direction than in longitudinal direction, the tendency of which was not altered in the normalized. Residual stresses in ERW tubes in their longitudinal direction were extremely large in comparison with UO-forming tubes and Bending-roll tubes. Dimensional deviations from nominal sizes were small enough to satisfy the JIS tolerances, but not always met European Standards.
