A kind of hot-rolled wire rod with tensile strength of 4000mpa class cord and its production method

Abstract

The invention relates to a hot-rolled wire rod for a cord thread with tensile strength being the 4000MPa grade. The hot-rolled wire rod is prepared from the components in percentage by weight: 0.71 to0.75 percent of C, 0.36 to 0.40 percent of Si, 0.10 to 0.14 percent of Mn, less than or equal to 0.01 percent of P, less than or equal to 0.01 percent of S, 0.10 to 0.25 percent of Cr, and 0.0005 to0.0015 percent of B. A production method comprises the steps of smelting through a converter; carrying out RH vacuum treatment; continuously casting into small square ingots; slow cooling the ingot blanks; heating the ingot blanks; rolling at high speed; spinning; and air cooling for standby use. According to the hot-rolled wire rod for cord thread with tensile strength being the 4000MPa grade andthe production method provided by the invention, through reducing the content of carbon, improving the content of silicon, and adopting the matched process, on the premise of ensuring the tensile strength to be larger than 4000MPa, the diameter of a wire material reaches to 3.0 to 3.5mm, so that the fracture surface of the wire material is homogenized in structure and better in performance, gammacrystal particles are micronized, the aging during wire drawing processing is inhibited, and the fracturing of a cementite is inhibited; and the strength and the wire drawing limit of the wire material are improved, the times of stranding filament break does not exceed 2 times / ton steel, and secondary processing by a user can be omitted and simplified, so that the production cost is reduced, andthe production efficiency is improved.

Description

technical field [0001] The invention relates to a wire rod and a production method thereof, belonging to a wire rod for an ultra-high-strength cord and a production method thereof, in particular to a hot-rolled wire rod for a cord with a tensile strength of 4000MPa and a production method thereof. Background technique [0002] With the vigorous development of the automobile industry, the domestic demand for cord steel as the skeleton material of tires exceeds 2 million tons and is increasing year by year. [0003] Cord steel is the best among wire products, known as "the jewel in the crown". Its requirements: the final diameter is small (up to 0.15mm), and the drawing length per ton of steel exceeds 3,000 kilometers, which is relatively difficult for producers; and there is: the user's deep processing process is long and complicated, that is, it needs to go through dozens of passes Drawing and heat treatment process, and at the same time, the compression rate of the steel w...

AI Technical Summary

Problems solved by technology

To sum up, the smelting and rolling of eutectoid steel and hypereutectoid steel all face insurmountable technical problems, resulting in fluctuations in product quality and quality complaints from users

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