Coil rod used for 70-grade cord thread outer winding wire and production method of coil rod

Abstract

The invention provides a coil rod used for a 70-grade cord thread outer winding wire. Steel of the coil rod comprises, by weight, 0.68-0.72% of C, 0.20-0.45% of Mn, 0.20-0.40% of Si, 0-0.010% of P, 0-0.010% of S, 0.0003-0.0008% of Mg, 0.0002-0.006% of Ca, 0.0015-0.0025% of total oxygen, 0-0.05% of Cu, and the balance Fe and inevitable impurities. A production method of the coil rod comprises the steps that the LF refining temperature is 1540-1590 DEG C, and the refining time is 60-120 minutes; the superheat degree of molten steel of a continuous casting tundish is not larger than 30 DEG C; the cooling speed of the coil rod before phase change after rolling is 10-15 DEG C / s, the temperature when phase change begins is 650-670 DEG C, and the reel collecting temperature of the coil rod is 250-400 DEG C. The content of sorbite of the produced coil rod is 65-80%, and the wire broken rate is not lager than 0.4 time per ton.

Description

technical field [0001] The invention belongs to the field of wire rods for fine processing, and in particular relates to wire rods for wrapping 70-grade cords and a production method thereof. Background technique [0002] As the competition in the domestic steel cord market intensifies, the demand of domestic manufacturers for domestic wire rod suppliers to replace imported wire rods continues to increase. The outer winding part of the steel cord requires the diameter of the steel wire to be small, and the 70-grade wire rod generally has a processing diameter of 0.13-0.15mm, and requires a low wire breakage rate during the outer winding process, which should not exceed 1 time per ton. This puts forward higher requirements for the production of wire rods for outer winding. In order to achieve the purpose of smoothly producing outer winding wire for steel cord, it is necessary to strictly control the sorbite content of the wire rod to ensure the cold working performance of th...

AI Technical Summary

Problems solved by technology

The high-carbon steel wire rod has excellent mechanical properties, less alloy elements, and low cost, and its preparation process is only obtained by slightly adjusting the existing high-carbon steel wire rod production process, which hardly increases any production cost; The disadvantage is that in terms of wire rod cooling, it only introduces the spinning temperature of the wire rod, and the process of rapid cooling of the wire rod before and at the beginning of the phase change, and slow cooling after the phase change, without specifying the specific cooling process parameters. At the same time, it did not introduce the wire rod for outer cord winding and the control method of its sorbite

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