Method for reducing thickness of oxide scale on surface of hot-rolled steel sheet

Abstract

The invention discloses a method for reducing the thickness of oxide scale on the surface of a hot-rolled steel sheet. The method for reducing the thickness of the oxide scale on the surface of the hot-rolled steel sheet comprises the steps of dephosphorization before rough rolling of a continuous casting billet, and control over rough rolling, wherein the total deformation of the rough rolling is 70%-85%, and the rolling reduction of passes of the rough rolling is controlled to be equal. The process of rough rolling is controlled, the pass load is distributed again, the rolling reduction of the passes can be equal, and the body surface of a slab is gradually increased along with reduction of the temperature. The body surface ratio of the slab in each pass is smaller than that of a slab in a corresponding pass in a rolling method that the rolling reduction decreases pass by pass under the premise that the total deformation of the rough rolling is the same, thus, the purpose of reducing the thickness of the oxide scale and the purpose of pressing the oxide scale are achieved, the surface quality of the hot-rolled steel sheet is improved, the acid amount and the time for acid pickling in the follow-up working procedure are reduced, and production efficiency and metal yield are improved. When the method for reducing the thickness of the oxide scale on the surface of the hot-rolled steel sheet is adopted, the size of a recrystallized austenite grain can be reduced, and the method for reducing the thickness of the oxide scale on the surface of the hot-rolled steel sheet is beneficial to obtaining even microstructures, and improves strength, ductility and toughness of the hot-rolled steel sheet.

Description

technical field [0001] The invention relates to a steel rolling process control technology, in particular to a method for reducing the thickness of oxide scale on the surface of a hot-rolled steel plate. Background technique [0002] At present, the development of hot rolling technology mainly focuses on the precise control of plate shape, thickness accuracy, temperature and performance. With the rapid development of the automobile and home appliance industries, downstream users have increasingly stringent requirements for steel surface quality. Quality objections or even product returns are often caused by improper control of surface oxide scale, which seriously hinders the improvement of product grades. In the past, pickling, cold rolling, hot-dip galvanizing or coating have been used for surface treatment. In recent years, the introduction of energy-saving and emission-reduction guidelines has prompted downstream industries to meet increasingly stringent environmental pro...

AI Technical Summary

Problems solved by technology

[0007] However, the above method has the following problems: 1) reducing the slab heating temperature or holding time is not conducive to the homogenization of alloy elements in the steel, and is likely to cause defects such as dendrite segregation and banded structure; 2) reducing the rough rolling and finishing rolling temperatures It will affect the subsequent cooling process and microstructure uniformity, and the finishing temperature is too low, which is easy to cause mixed crystals; 3) The control of silicon content increases the difficulty of smelting and will affect the final mechanical properties of the steel; 4) Control the front section Rapid cooling puts forward higher requirements for existing cooling equipment; 5) Adding iron oxide scale removal device increases facilities and investment

Images