Hot-rolled wire rod for galvanized steel wire of bridge cables above 2000mpa and its production method

Abstract

The invention relates to a hot-rolled wire rod for galvanized steel wires of bridge cables above 2000 MPa. The chemical composition of the product is calculated by weight percentage: C: 0.90-1.10%, Si: 0.20-0.60%, Mn: 0.30-0.90% , P≤0.010%, S≤0.005%, Cr: 0.10‑0.40%, Al: 0.010‑0.070%, V: 0.02‑0.15%, Cu: ≤0.05%, Ca: 20‑40ppm, N: 20‑90ppm, Others are Fe and unavoidable residual elements; the sorbite structure content of the wire rod is ≥95%, and the tensile strength of the through circle is poor ≤70MPa (uniformity). After the wire rod is drawn and galvanized, the galvanized steel wire is tensile Strength ≥ 2000MPa, torsion times ≥ 12 times. The process flow of the wire rod, molten iron pretreatment, converter or electric furnace steelmaking, LF refining, RH degassing treatment—390*510 bloom continuous casting—billet reheating—billet rolling—intermediate billet surface finishing—intermediate billet reprocessing Heating—rolling of intermediate slab—on-line EDC water bath toughening treatment of wire rod—collection and packaging of wire rod.

Description

technical field [0001] The invention belongs to the technical field of steel wire production, and more specifically relates to a hot-rolled wire rod for galvanized steel wires of ≥2000MPa high-strength bridge cables and a production method. Background technique [0002] The data shows that for every 100MPa increase in the strength of the bridge cable steel wire, its own weight can be reduced by 10%, the cable diameter is correspondingly reduced, and the windward resistance is correspondingly reduced, thereby reducing the influence of the bridge on the wind force and direction. [0003] With the continuous advancement of iron and steel enterprise technology, the strength records of galvanized steel wires used for bridge cables are constantly updated, ranging from 1670Mpa, 1770Mpa, 1860Mpa, 1960Mpa to the current 2000Mpa. While the strength level meets the requirements, there are also strict requirements on the torsion index of the steel wire. The level of the torsion index di...

AI Technical Summary

Problems solved by technology

Due to the low cooling rate of the wire rod by the air-cooling process, the sorbite content of the structure is below 90%, the tensile strength of the wire rod is very poor at about 100MPa, and the upper limit of the production specification can only reach Φ13.0mm, which is in line with galvanized steel wire. The wire rod required by the index can only meet the level of 1860MPa, and there is no domestic example of online mass production of wire rod at the level of 2000MPa; the use of online air cooling of wire rod + offline salt bath (or lead bath) heat treatment process of wire rod requires the The wire rod is air-cooled to room temperature, and then the wire rod is laid out into a straight line into the heating furnace for re-austenitization heating. After being released from the furnace, it is cooled in a salt bath or a lead bath. This process consumes a lot of energy, has a great impact on the environment, and has low production efficiency. Does not meet the low energy consumption and green environment-friendly production process advocated by the state

[0006] At present, the patent information publicly published in China includes: Chinese patent publication number CN 104624680A involves the production of off-line EDC. The steel wire used for rope making has not been practically applied to the production of galvanized steel wire for bridge cables

[0007] The patent publication No. CN 102719643A involves quickly placing hot-rolled wire rods into lead tanks or salt tanks for sorbitization of wire rods. The cooling medium for wire rods is lead liquid or salt liquid, which is more corrosive to equipment. It is large and pollutes the environment to a certain extent. The wire rods produced are mainly used to manufacture steel wire ropes, and have not been practically applied to the production of galvanized steel wires for bridge cables.

The production process is that the continuous casting slab is rolled into a wire rod, and the wire rod is reheated and austenitized and then heat treated in an off-line salt bath. The production cost is high and the production efficiency is low.

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