Effect of Reduction in Three-Drawn and Two-Drawn Single-Run Technology on Roughness of Inner Surface of Tubes

The paper deals with the production of could drawn precision seamless steel tubes with three-drawn and two-drawn single-run technology. The aim of experiment is to verify the possibility of drawing rolled tubes of size ∅ 70 × 6.3 mm (material E355) with three-draw single-run technology without intermediate recrystallising annealing on the final size ∅ 44 × 3 mm in the fixed reduction and two-draw single-run technology ∅ 70 × 6.3 mm without intermediate recrystallising annealing on the final size ∅ 50 × 3.75 mm in the fixed reduction and with size ∅ 70 × 6.3 mm without intermediate recrystallising annealing on the final size ∅45 × 3.75 mm in the fixed reduction. Advise the impact choice of the reduction on roughness of inner surface of tubes.