The Change of Mechanical Properties of Material Using Various Reductions by Cold-Drawn Precision Seamless Tubes

摘要

The production of cold-drawn precision seamless tubes has an old tradition in Zeleziarne Podbrezova a.s. The production itself consists as a final operation of two previous operations, namely: steel plant - production of continued casting billet and hot-rolling plant - production of hot-rolled tubes. At steel plant, steel is produced in electric arc furnace with following continuous casting. The final product is biller with dimensions 200 x 200 x 400 mm. At hot-rolling plant, hot-rolled tubes serve as feed stock for cold-drawing. A hot-rolled tube can be adjusted to feed stock of cold-drawing plant from the material as well as from dimensional point of view. Based on these possibilities, technological process of production - number of passes, heat treatment and percentage of reduction can be altered by technologists. In this paper, we dealt with number of operations in technological processes of cold-drawing plant. As we have already mentioned, passes, reductions and heat treatment can influence the final tube in terms of mechanical properties (R 02, Rm, A5, HV) and microstructural states.