The development trend of welded pipe rolls

The development direction of cold rolls will be to further improve the strength, hardness and depth of the hardened layer, while ensuring a certain degree of toughness. Large-scale cold-rolling work rolls will generally be made of improved 5% Cr steel containing vanadium, milling, nickel and other elements. In order to improve the hardenability of the material, the content of Cr will be further increased. For example, forged steel with 8% ~ 10% Cr and higher chromium has begun to be used in actual production, but the increase in the Cr content will lead to poor toughness, so It is necessary to properly balance the content of C and Cr, and quench at a lower temperature to obtain the required hardness of the cold roll, thereby reducing the fracture of the roll and reducing its fracture sensitivity.

In addition, with the further improvement of forging manufacturing technology, high-chromium steel work rolls will be more used in large-scale cold rolling mills. 5%Cr and its vanadium-containing improved steel are widely used in large-scale back-up roll forgings, and large-scale forged steel back-up rolls with high chromium content have entered the practical stage. Large-scale cold-rolling work rolls are required to be forged with electroslag remelting ingots, while steel for large-scale support roll forgings is widely produced by ladle refining and vacuum degassing smelting process, and the purity of molten steel has reached a high level.

Hot rolls work under the action of alternating high temperature and force, and the surface is repeatedly rubbed, resulting in strong wear. Therefore, the development of hot rolls is mainly to further improve their wear resistance. In actual vehicle production, hot rolls with surface hardening and carburizing treatment can no longer meet the requirements for their high wear resistance, but the overall high-speed steel or cemented carbide rolls are extremely costly, and the material for the core of the roll is very low. Cause waste. Therefore, the production of rolls urgently needs surface treatment, and cemented carbide or ceramic materials are cladding on the surface of the roll as the working surface of the roll. Surface chromium plating, flame spraying, plasma spraying and laser texturing are all tool surface alloy strengthening technologies, which will be further used to improve the performance of the roll.

In short, reasonable selection of materials and the use of suitable heat treatment methods to produce high-quality rolls can save a lot of roll materials, reduce the cost of steel rolling, and improve the quality and output of the rolls. Therefore, we should pay attention to the new trend of roll material selection, develop new roll materials based on the actual conditions of steel rolling, and improve the manufacturing quality of rolls.