Post-rolling cooling control method for small-size high-Cr 82B wire rods

Abstract

The invention relates to a post-rolling cooling control method for high-Cr (the alloy content accounts for 0.30 percent-0.35 percent) SWRH82B wire rods. The method comprises the steps that post-rolling spinning temperature, cooling speed before spinning phase change, phase-transition temperature range, phase-transition cooling speed, Stelmor roller speed, fan delivery and Jialing air distribution are combined and controlled, and production equipment is adjusted to stabilize spinning mode so that the purpose of the stable production can be achieved. The spinning temperature is controlled to range from 860 DEG C to 880 DEG C. The cooling speed before post-rolling phase-transition is controlled to range from 10.0 DEG C/s to 14.0 DEG C/s. The phase-transition temperature is controlled to range from 580 DEG C to620 DEG C. The cooling speed in a phase-transition area is controlled to range from 1.5 DEG C/s to 3.0 DEG C/s. The base speed of the inlet segment of a Stelmor roller bed is controlled to range from 0.6 m/s to1.0m/s. After the technical scheme of the post-rolling cooling control of the wire rods is applied and implemented, it can be guaranteed that high strength is achieved, and plasticity does not decrease but is improved. Moreover, the situation that as cleaning rods are cooled in a non-uniform mode, so that the local positions produce low-temperature shift tissue such as martensite is avoided, and the uniformity of the cleaning rod tissue and the mechanical performance is guaranteed.

Description

technical field [0001] The invention belongs to the technical field of controlled rolling and controlled cooling of steel rolling, and in particular relates to a post-rolling controlled cooling technology of small-sized high-chromium 82B wire rod. Background technique [0002] As the main raw material of prestressed steel wire and steel strand, SWRH82B is widely used in highways, railway bridges, high-rise long-span buildings, seaport terminals and sleeper industries. In order to meet the high-strength requirements of wire rods for export without reducing the plasticity, large-scale (Φ≥8.0mm) are added with hardenable micro-alloying element Cr, but the content generally does not exceed 0.25%. ≥8mm) with low Cr content (Cr≤0.25%) has been researched and developed more and there are related reports. Whether it is domestic or foreign small size (Φ5.0-7.0mm) 82B wire rod, the tensile strength of the user is generally ≥1180MPa when delivered, and the desired target is ≥1200MPa, ...

AI Technical Summary

Problems solved by technology

The content of Cr should not be too high, especially for small specifications. Compared with large specifications, due to the smaller section diameter, its hardenability will be stronger, which will cause the continuous cooling CCT curve of the wire rod after rolling to move to the right downward. Then the critical cooling rate for forming martensite is greatly reduced. If the cooling process is slightly improper, it is very easy to produce low-temperature transformation structures such as martensite and bainite. High requirements, which bring great difficulties to the control of abnormal microstructure and mechanical property fluctuations of controlled cooling after rolling