engleski

INFLUENCE OF NIOBI ON QUALITY HIGH-FREQUENCY WELDED PIPE

In order to investigate the cause of the appearance of Lüders lines on cold drawn pipes, studies of welded pipes were carried out, which were subsequently formed by cold-drawn to the final dimensio. Studies were conducted on low carbon steel without niobium and low carbon steel with the same base chemical composition but with 0, 047% addition of micro-alloying element niobium. The pipe are welded using a high-frequency process. The mechanical properties of the pipe were tested. Structural tests were carried out on the weld, the the zone of heat affected and the base material of pipe. Niobium microalloyed pipes have significantly better mechanical properties than niobium-free pipes. Luders band have been found to occur only in niobium microalloyed steel.

Niobium micro-alloyed steel, pipes, high frequency welding, cold drawing, Lüders band

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