THE INFLUENCE OF TIG WELDING JOINT ON PLASTICITY OF SEAM TUBES

This article is focused on analysis of state formation which influences the tubes production process from austenitic stainless steels with diameter circle divide 0.34 mm in a negative way. The problems have been concentrated on factors monitoring which affect the drawing process stability of seem tubes where the desired final dimensions - a diameter circle divide 0.34 mm and a wall thickness 0.057 mm have been limited factors. The seem tube from steel 1.4306 and 1.4301 from producers KRUPP THYSSEN and ERGSTE WESTIG with longitudinal weld line created by TIG welding has been used as a blank for constituent drawing operations. By means of a weld analysis it has been determined that a thermal field creating during a weld formation can cause such material changes which influence to plasticity in a negative way during constituent drawing operations. There is a danger of chromium carbide precipitation along grain boundary in heat affected zone if a weld thermal field isn't sufficiently cooled. These carbides cause plasticity degradation during technological operations with the most intense strain. It is desirable to provide intense inert gas circulation during a weld creation in air protective chamber.