Lutsenko O. Improvement of the chemical composition and cooling modes at wire-rod termomechanical treatment for the high-strength side wire

High carbon steel wire rod. The improvement of chemical composition and cooling modes under thermo mechanical treatment of high-carbon wire-rod, providing production of high-tensile bead wire without intermediate heat treatment. Metallographic, dilatometer, X-ray methods of mathematical modeling. The kinetics of austenite of steel 90 transformations with different content of carbon, chrome and manganese is studied at continuous cooling and isothermal conditions. It is found that increasing of the chromium content (from 0.02% to 0.24%) and reduction of manganese (from 0.44% to 0.30%) and carbon (from 0.92% to 0.87%) in the steel 90 under cooling rate of 17°C/sec decreases austenite transformation end temperature by 10°C, which reduces the interlamellar spacing of the pearlite by 12%, but leads to the formation of the bainite, which under cooling rate of 15°C/sec or less is absent, but in isothermal conditions (550°С) increases the time of austenite’s decomposition by 25%. It is found that the thermo mechanical treatment under cooling rate of 12-15°C/sec of the high-carbon wire-rod with chromium content of 0,21±0,04% and manganese content of 0,3±0,03% ensures the increasing of sorbitic pearlite, allowing without intermediate heat treatment eliminate the stratification of high-tensile bead wire in twisting. The results are used for wire rod and high-tensile bead wire technology improvement at OJSC "Belarusian Metallurgical Plant". Metallurgy. Applied in industry.