Method for preventing surface oxide film of nichrome roller from being peeling-off

Abstract

A method for preventing the surficial oxide film of Ni-Cr roller from being stripped includes such steps as blooming the conticast billet of ferritic stainless steel at 1150 + / - 50 deg.C to become intermediate billet at 1020-1050 deg.C and with a thickness less than 35 mm, arranging an insulating hood between blooming and finish rolling, and finishing rolling of stainless steel band at a temp higher than 950 deg.C by three passes with relative surface roughness of rollers (0.9 microns, 0.6 microns and 0.6 microns) and relative maximal deformation rate (42%, 38% and 36%).

Description

technical field [0001] The invention relates to a method for preventing the peeling off of the oxide film on the surface of a nickel-chromium roll, in particular to a method for preventing the peeling off of the oxide film on the surface of a high-nickel-chromium roll when rolling ferritic stainless steel. Background technique [0002] Due to the change in the demand direction of the stainless steel market, the demand ratio of ferritic stainless steel has increased from 10% to more than 30%, and the increasing trend remains unabated. However, when high Ni-Cr rolls are used to produce ferritic stainless steel hot-rolled strips In the process of steel production, there has always been the phenomenon of peeling off of the oxide film on the surface of the roll, which causes the surface of the roll to be rough, resulting in a serious increase in the roughness value of the surface of the hot-rolled strip produced, thereby reducing the surface quality of the cold-rolled product. Th...

AI Technical Summary

Problems solved by technology

[0002] Due to the change in the demand direction of the stainless steel market, the demand ratio of ferritic stainless steel has increased from 10% to more than 30%, and the increasing trend remains unabated. However, when high Ni-Cr rolls are used to produce ferritic stainless steel hot-rolled strips In the process of steel production, there has always been the phenomenon of peeling off of the oxide film on the surface of the roll, which causes the surface of the roll to be rough, resulting in a serious increase in the roughness value of the surface of the hot-rolled strip produced, thereby reducing the surface quality of the cold-rolled product

This problem has become one of the main factors restricting the rapid development of ferritic stainless steel. Domestic and foreign stainless steel hot rolling mills have long been committed to the research on the peeling off of the oxide film on the surface of the roll, and proposed methods to prevent the peeling off of the oxide film on the surface of the nickel-chromium roll. The most typical The best method is to increase the rolling temperature. The suitable processing temperature for ferritic stainless steel hot rolling is 900°C-1100°C. Hot rolling in this temperature range is most likely to cause bonding between the strip steel and the rolls of the front stand of the finish rolling. The oxide film on the surface of the roll is peeled off. In order to prevent the occurrence of roll sticking, the rolling temperature in foreign countries is increased to above 1260°C, so that the rolling temperature of the front stand of the finishing rolling avoids the temperature that is prone to sticking. At the same time, the price of the front stand is higher High-speed steel rolls about five times higher than Ni-Cr rolls are used as work rolls. This method has the following disadvantages: (1) increasing the rolling temperature causes excessive growth of continuous casting slab grains, which seriously affects the cold workability of stainless steel products; (2) ) Although the front frame of the finish rolling avoids the temperature that is prone to sticking, the rear frame still cannot avoid this temperature range, and there are still different degrees of sticking; (3) The cost of using high-speed steel rolls is expensive and the use Harsh conditions bring a lot of inconvenience to production control and high cost