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How to use high-speed steel rolls
Release Time：
2025-03-19
High-speed steel rolls contain a large amount of alloying elements such as W, Mo, Cr, V, and Co. High-speed steel rolls have superior hardness, resistance to thermal cracking, and resistance to thermal shock compared to high nickel-chromium cast iron rolls, and their wear resistance is 4-5 times that of high nickel-chromium cast iron rolls.
High-speed steel rolls contain a large amount of alloying elements such as W, Mo, Cr, V, and Co. High-speed steel rolls have better hardness, resistance to thermal cracking, and resistance to thermal shock than high nickel-chromium cast iron rolls, and their wear resistance is 4-5 times that of high nickel-chromium cast iron rolls. Therefore, high-speed steel rolls have been rapidly promoted in hot rolling production. The following aspects should be noted in the use of high-speed steel rolls:
1. Roll surface temperature control
High-speed steel rolls have a large amount of thermal expansion. Uneven temperature distribution easily causes uneven thermal expansion and abnormal shedding of the oxide film, affecting the thermal camber and roll gap accuracy of the rolls. The key factor affecting the oxide film and thermal camber of high-speed steel rolls is the roll surface temperature.
Therefore, the ideal roll cooling method and shortening the time the roll surface is at a high temperature are important means to control the thickness of the oxide film on the roll surface, control the thermal camber, and reduce thermal cracks. The instantaneous contact temperature of the roll during hot rolling is 600-750℃. After the roll surface leaves the contact arc, the temperature must be quickly reduced from 700℃ to below 300℃ to prevent further oxidation. After the roll passes through the instantaneous high-temperature contact zone, quickly working in a 100% water-cooled environment is conducive to the formation of an oxide film with optimal protective performance. Optimizing the distribution of roll cooling water, such as increasing the amount of cooling water on the outlet side, increasing the amount of cooling water in the middle of the roll, and reducing the height of the cooling water pipe, can significantly reduce the roll surface temperature.
2. Control roll cracks
In the process of using high-speed steel rolls, thermal fatigue causes thermal cracks on the surface of the rolls, which is difficult to avoid. However, if they are still used after thermal cracks appear, or if the cracks are not completely ground away during grinding, the cracks will continue to expand during further use, resulting in pitting. Therefore, during the use of high-speed steel rolls, it is crucial to control the operating conditions of the rolls and their maintenance.
3. Roll and groove changing operations
When steel sticking or piling occurs on the roll groove during the production use of high-speed steel rolls, the water should be stopped immediately, the upper roll should be quickly lifted to allow the rolled material to leave the roll surface, and the rolled material piled up on the lower roll should be immediately removed. Allow the heated roll groove to cool naturally in the air. When restarting production after accident handling, the groove must be changed, and it should be changed every 2-3 grooves. Cooling water is absolutely not allowed to rush to or flow to the heated roll groove. If it is indeed unavoidable and the groove cannot be changed, the roll must be changed and allowed to cool naturally before being reinstalled.
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