A control method for reducing the yield-strength ratio of low-carbon cold heading steel

Abstract

The invention relates to a controlling method for lowering the yield ratio of low-carbon cold heading steel, and belongs to the technical field of steel rolling. The controlling method is used for controlling the yield ratio of low-carbon cold heading steel hot-rolled wire rods. The temperature for finish rolling is controlled, and in the rolling and deformation process, solid solution N in the steel is controlled to be separated out in the austenitic area in the form of large-size AlN. Meanwhile, coarse austenite grains caused by over-high rolling temperature or mixed crystal caused by rolling in part of recrystallization zones due to over-low finish rolling temperature is avoided, and a large-area coarse grained Widmanstatten structure is generated after rolling. The temperature for wire forming is controlled to be 860DEG C-900DEG C, and a heat holding cover is opened. According to roller speed control of a Stelmor air-cooled line, the cover feeding temperature is controlled to be 700DEG C-750DEG C, and the cover discharging temperature is controlled to be 550DEG C-600DEG C, wherein the average cooling rate in the cover is controlled to range from 0.4DEG C / s to 0.6DEG C / s, and retarded cooling time is 260s-420s. The solid solution N in the steel is separated out in the form of AlN with a small size of 20nm-60nm in a ferrite area. The controlling method has the advantages that the yield ratio of the hot-rolled wire rods is effectively controlled, the probability of work hardening of deep drawing of the hot-rolled wire rods is remarkably lowered, the wire breakage rate and the loss of a grinding tool are lowered, and the service life of the wiredrawing grinding tool is greatly prolonged.

Description

technical field [0001] The invention belongs to the technical field of steel rolling, and in particular provides a control method for reducing the yield ratio of low-carbon cold-heading steel, which is applied to high-speed wire factories to produce low-carbon cold-heading steel hot-rolled wire rods. Background technique [0002] The advancement of technology in the deep processing industry has continuously increased the drawing rate of the wire rod, greatly improving the production efficiency. Among them, about 60-70% of the drawing work is transformed into the deformation heat of the steel wire. The increase of the deformation heat causes the steel wire to have obvious deformation and aging in the production process, and then the plasticity deteriorates and the wire breaks. The index also puts forward requirements. In order to solve this problem, in addition to relying on the optimization of the alloy composition of the material, the high-speed wire factory must continuous...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a control method for reducing the yield ratio of low-carbon cold heading steel, which solves the problem of high yield ratio of low-carbon cold heading steel hot-rolled wire rods, and is suitable for optimizing and adjusting the production process of high-speed wire rod factories. Including finishing temperature control, spinning temperature control and Stelmore air-cooled line heat preservation temperature and slow cooling speed control

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