Surface treatment method for loop back rolls of hot continuous rolling units

Abstract

The invention discloses a surface treatment method for loop back rolls of hot continuous rolling units, and the method comprises the following steps of: firstly, carrying out cleaning pretreatment on the surface of a loop back roll, and carrying out overlay welding on the surface of the loop back roll by using a hard-surface alloy welding wire so as to form a middle transition layer with the thickness of 2-3 mm, wherein the overlay welding current is 380-450A, the voltage is 26-30V, and the overlay welding speed is 300-400 mm / min; then, preparing a work coating with the thickness of 0.5-2 mm by using a spray welding remelting way, wherein the work coating is made of a Ni-based alloy powder material, the distance between a spray gun and the surface of a workpiece is 250 mm, the powder feeding speed is 50-150 g / min, and the gas pressures of acetylene and oxygen are respectively 0.1-0.3 MPa and0.1-0.5 MPa; and finally, carrying out remelting treatment on the work coating by using an oxyacetylene flame gun, wherein the flow rates of acetylene and oxygen are respectively 1 kg / cm<3> and 4.5 kg / cm<3>, and the remelting temperature is 800-1200 DEG C. The method disclosed by the invention can be used for improving the wear resistance and corrosion resistance of the surfaces of loop back rolls, prolonging the service lives of the loop back rolls, ensuring the normal operation of hot continuous rolling units, and improving the quality and production efficiency of strip steel rolling.

Description

technical field [0001] The invention relates to a surface treatment method for looper rolls of a hot continuous rolling mill. Background technique [0002] In the hot strip rolling process, the mechanical properties of hot rolled products are mainly determined by the finishing rolling process. With the diversification and high-level requirements for the mechanical properties of hot-rolled products, the requirements for finish rolling are also getting higher and higher. At present, most of the finishing rolling adopts 6-stand or 7-stand rolling, and the looper roll plays an important role in the formation and stability of the continuous rolling relationship. In the hot continuous rolling process, the speed of the strip steel is different after being rolled by the front and rear rolling stands, and the strip steel produces a wrap angle on the looper roll, and the tension of the strip steel makes the looper roll subject to a certain radial load, and the looper roll The pressu...

AI Technical Summary

Problems solved by technology

Generally, the surface of the looper roll is surfacing with 2Cr13 material. The surface is easily corroded by the cooling liquid in the rolling process, and rust spots are formed on the roll surface. Corrosion occurs, and the wear resistance is relatively poor

If the rust spots on the roll surface fall off, the strip will be pressed into the strip during the subsequent rolling process, which will affect the quality of the strip

Moreover, during the friction process between the looper roll and the strip steel, it is easy to wear and fail, forming striped wear marks, which affects the quality of the strip steel

If the looper rolls wear unevenly, one end of the roll surface is large and the other end is small, which will also affect the shape of the strip after subsequent rolling.

After the looper roll has been used for a period of time, in order to continue to use it, the surface of the looper roll has to be ground. This not only affects the normal operation of the hot continuous rolling mill and the production efficiency of strip rolling, but also reduces the efficiency of the looper roll. service life, and cannot fundamentally improve the wear resistance and corrosion resistance of the looper roll surface