The Application of a Factorial Experiment with Repeated Measurements in the Investigation of Parameters Influencing the Properties of Niobium Microalloyed Cold Drawn Welded Steel Tubes

Sa？etak It has been observed that inhomogeneous deformations occur at the beginning of the plastic material flow during the cold drawing of welded tubes and after the proportionality limit Rp has been reached. Therefore, it is important to determine the most influential factor at the beginning of the plastic material flow. Tests were carried out on a welded joint and on the base material. The study was performed on two steels with different contents of the microalloying element niobium. Tubes were drawn with two different degrees of reduction. The factorial experiment consisting of three factors at two levels 2^3 with repeated measurements showed that the degree of reduction has the greatest influence on the proportionality limit