METHOD OF PRODUCTION OF THE ROLLED SECTION STEEL IN THE FORM OF BARS MADE OUT OF THE MEDIUM-CARBON CHROMIUM-CONTAINING STEEL

摘要

FIELD: metallurgy industry; method of production of the circular rolled section steel in the form of circular bars made out of the medium-carbon chromium-containing steel.;SUBSTANCE: the invention is pertaining to the field of metallurgy, in particular, to production of the circular rolled section steel made out of the medium-carbon steel of the heightened cutability and used for manufacture of the ball studs, the tie-rod ends and the ball supports of the motor car suspension produced by the method of the cold die forging. The technical result of the invention is the increased characteristics of the cutability at the simultaneous raise of the characteristics of the hardenability at provision of a throughout hardenability of the rolled section steel bars of up to 25 mm diameter, and also at conservation of the high level of the technological pliability of the steel. For realization of the technical problem the invention presents the method of production of the circular rolled section steel from the medium alloy steel includes the smelting of the steel in the electric furnace, the metal tapping from the furnace, the deep metal deoxidation by aluminum and the doping, the metal dressing in compliance with the chemical composition for all the components, except for aluminum and sulfur, reoxidation of the metal and the slag by the oxidized pellets, addition of aluminum, the treatment with calcium, the microalloying by sulfur with production of the steel at the following ratio of the components (in mass %): carbon - 0.35-0.420, manganese - 0.50-0.80, silicon - 0.17-0.37, chromium - 0.8-1.1, sulfur - 0.020-0.040, vanadium - 0.005-0.020, calcium - 0.001-0.010, oxygen - 0.001-0.015, nickel - up to 0.25, copper - no more than 0.25, molybdenum - no more than 0.10, arsenic - no more than 0.08, nitrogen - no more than 0.015, iron and the inevitable impurities - the rest, at fulfillment of the ratios: oxygen/calcium = 1-4.5 and calcium/sulfur ≥ 0.065, the continuous casting of the steel with protection of the spray by argon, the hot rolling of the continuous casting blank with usage of the mode of the thermomechanical working, winding the bars into the bars coils, the bars coils uncoiling, the bars cutting into pieces of 6 m length with accuracy of the cutting of ±5 mm, finishing the rolled metal by the roll dressing, inspection of the surface defects and the ultrasonic control of the internal flaws, the sample abrasive dressing, the solid abrasive polishing and the turning.;EFFECT: the invention ensures the increased characteristics of the cutability at the simultaneous raise of the characteristics of the hardenability at provision of a throughout hardenability of the rolled section steel bars of up to 25 mm diameter and also at conservation of the high level of the technological pliability of the steel.;1 ex