The invention discloses ultrafine
bainite bridge cable steel and a preparing method thereof, and belongs to wires for bridge cables and production thereof. The thermo-mechanical treatment + isothermalquenching technology is adopted for obtaining the cable steel; pre-deformation and low-temperature
bainite isothermality are combined, refining technologies of microalloy refinement, controlled rolling and cooling refining, pre-deformation and low-temperature
bainite isothermality are comprehensively used, an ultrafine bainite structure composed of non-
carbonization bainite and retained austeniteis obtained, the tensile strength of the structure ranges from 1800 to 2100 MPa, and the
ductility of the structure ranges from 12 to 20%; the preparing process of the ultrafine bainite bridge cablesteel comprises the steps of
smelting,
continuous casting, hot rolling,
cutting, austenitizing, pre-deforming and low-temperature bainite isothermality. During pre-deforming, firstly, a
cut hot-rolledwire rod is heated again to Ac3+50 DEG C to be subjected to austenitizing, heat preservation is carried out for 0.5 to 1 h, rapid cooling (the
cooling speed is larger than 10 DEG C / s) to 220 to 280 DEG C is carried out, further warm rolling is carried out, the rolling reduction is 20 to 30%, then, the
wire rod is put into a
salt bath furnace at the temperature of 220 to 280 DEG C to be subjectedto isothermality treatment for 3 to 5 h, and isothermality bainite conversion is carried out; and the
wire rod is taken out and subjected to
air cooling to the
room temperature.