A control method for reducing edge linear defects of hot-rolled medium and high carbon alloy steel

Abstract

The invention discloses a control method for reducing edge linear defects of hot-rolled medium and high carbon alloy steel, comprising the following steps: 1) adopting conventional smelting and continuous casting to obtain right-angle continuous casting billets; 2) adopting direct loading of the continuous casting billets 3) Slab reheating; 4) After high-pressure water descaling, empty through the sizing machine or carry out small side pressure on the sizing machine; 5) Rough rolling mill R1 , R2 adopts "1+5" pass rolling; 6) R2 descaling pass for rough rolling is 1, 5 passes; 7) E2 vertical roll is used for width reduction, and the action passes are 1, 3, and 5 passes; 8) The thickness of the rough-rolled intermediate billet is set to 50-58mm, and the RT2 outlet temperature is ≥1080°C; 9) After seven-stand finishing rolling, it is coiled into steel coils. The proportion of defects in the longitudinal direction of the steel coil of the present invention is reduced to less than 2%; the position of the defect from the edge is reduced to less than 10 mm.

Description

technical field [0001] The invention relates to the technical field of rolling process control of hot-rolled medium and high carbon alloy steel, in particular to a control method for reducing edge linear defects of hot-rolled medium and high carbon alloy steel, belonging to the technical field of hot rolling technology. Background technique [0002] Hot-rolled medium and high carbon alloy steel is mainly used in the manufacture of automobile clutch spring diaphragms, saw blades, brake discs and other wear parts. Generally speaking, after the downstream user trims the original curling part (the maximum trimming amount is 10mm), the raw material is slit according to the finished product size. Therefore, if the customer operates as usual, the surface of the strip will have defects more than 10mm away from the edge. It will be inherited to the finished parts, which will cause huge hidden dangers to the safety of downstream users; if the customer increases the amount of trimming,...

AI Technical Summary

Problems solved by technology

It mainly obtains the continuous casting slab with good temperature uniformity by controlling the heating process, and then controls the width reduction of rolling to 50-200mm, the thickness of the intermediate slab to 32-46mm and the temperature of the edge of the slab at the entrance of the finish rolling ≥ 940°C. The method is very conventional. It has been proved by our practice that it has no obvious effect on the control of edge linear defects of hot-rolled medium and high carbon steel, and there is generally no measuring instrument for the edge inlet temperature, let alone a feedback control system, and the operability is not strong.

[0005] In addition, the Chinese invention patent application with the publication number CN 107096795 A discloses a manufacturing method for reducing edge defects of hot-rolled strip steel, which only reduces the load of the first pass of E1 by 1-5mm, and optimizes the distribution to the third pass of E1. The first and third passes of E2 and the optimization of vertical roller cooling water to less than or equal to 70%, reduce the edge temperature drop to reduce edge defects, from the perspective of its implementation effect: the amount of edge defect correction is only reduced by 60% %, and did not specifically quantify the degree of defect reduction, nor did it state the targeted steel types. After practice, this method is not suitable for edge linear defect control of hot-rolled medium-high carbon alloy steel

[0006] For optimizing the corner shape of continuous casting slab, such as adopting obtuse angle continuous casting slab (Chinese Invention Patent Application Publication No.: CN110405163 A), using arc-shaped width-sizing machine (Chinese Patent Publication No.: CN204583863U, CN110293136A), it has been proved by practice that due to the special The alloy composition system adopts this type of method not only unable to reduce the occurrence of linear defects at the edge, but even worsens such defects, so that the distance between such defects and the edge increases from 20-22mm to 30-35mm

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