W artykule prezentowana jest analiza problemu oraz wyniki badań odkształceń i ewolucji własności w kolejnych etapach przetwarzania taśmy na rury, w liniach zgrzewania. Wyniki wykorzystano do projektowania procesów technologicznych a w szczególności własności wsadu.
This paper presents results of analysis and tests of deformation and evolution of properties in subsequent stages of strip welded tubes production to achieve the required process stability level and properties of the product. The paper contains conclusions referring to requirements concerning the input material. Material passing along tube continuous forming and welding line is subjected to changes in structure and properties. Action of temperature is limited to the heat-affected zone (HAZ), where heat treatment effects is visible in mechanical properties and significantly decreased workability. Size of HAZ is determined with linear welding energy. Increase of temperature beyond HAZ resulted from the welding process does not cause any visible changes in mechanical properties of the material. It is possible to evaluate final mechanical properties of the material on the basis of known properties of the input material and equivalent deformation of material on the line (being a function of its technological parameters). On the basis of measurements of temperature distribution and rate of tube deformation in the welding system, and tests of soaking of material, we may state that there is no risk of occurrence of a physical yield point beyond HAZ. Model tests proved that input material with a physical yield point, in case of the identified line set-up, would not result in having a ready product with a yield point because deformation of material is large enough to eliminate it. The paper contains also results of research on implementation of heat treatment of the input strip. Influence of increased temperature on mechanical properties was also investigated.