Zhukova S. Development of selective requirements to chemical composition and practices of thermal and mechanical treatment of Sv-08G2S wire rod to attain the rod's improved deformability in the drawing

The wire rod from low-carbon Si-Mn electrical steel in Grade Sv-08G2C manufactured from the continuously cast steel billets of small cross section. The development of selective requirements to the chemical composition and thermomechanical processing of the Sv-08G2C wire rod ensuring direct welding wire drawing down to the size of 0.8 mm by eliminating intermediate annealing cycles. Metallographic, electron microscope, electron diffractometry, X-ray crystal, microroentgen & spectral, and dilatometric analyses were applied to determine the chemical composition of steel and mechanical properties of the rolled stock. The mass and technological properties of the mill scale were determined based on the procedures as described in national and international standards and regulations. The methods of mathematical statistics and simulation were applied to evaluate the experimental data, and to predict the mechanical properties. Тhe kinetics of transformation of the austenite in Si-Mn steel grade was studied, andthe thermokinetic diagram was designed. The martrensite transformation occurs after the bainite one within the cooling rates between 5.5…183 °С/с, however, at the cooling rates being lower than 5,5 °С/с, the austenite transformation is practically completed in the bainite zone. The specifications (TU) and a new softening thermomechanical processing for the Sv-08G2C wire rod have been designed and implemented at JSCC Moldova Steel Works and at a number of the Ukrainian, Russian and Belorussian wire drawers.