The invention provides an excellent-quality
steel bar controlled rolling and cooling method and belongs to the technical field of rolled steel production controlled rolling and cooling. The specific technological process comprises the step that controlled rolling and cooling of bars with the specification of the
diameter being 12-70 mm adopts short cooling, I section short temperature resetting, short cooling, II section long temperature resetting, short cooling, interrupt cooling and temperature resetting circular control technology. Short cooling adopts a
water cooling manner, I section controlled cooling, II section controlled cooling and III section controlled cooling adopt the short cooling manner, and the length of a cooler ranges from 500 mm to 1000 mm. Pressure of cooling water ranges from 0.5 MPa to 1.5 MPa, temperature resetting adopts an
air cooling manner, the I section short temperature resetting length is 1000-1800 mm, and the II section long temperature resetting length is 2400-3600 mm. According to the method, on the basis of meeting mechanical performance of bars, the problem that in the traditional controlled rolling and cooling technology, a deeper quenched layer is generated on the
surface layer is solved, generation of the quenched martensitic structure of the
surface layer is effectively avoided, control over organization types is achieved, meanwhile, better uniformity of the
surface layer and heart temperature is ensured, and the surface layer and heart
temperature difference is smaller than or equal to 50 DEG C.