Build up welding method for repairing cold rolling and leveling supporting rollers

Abstract

The invention discloses a build up welding method for repairing cold rolling and leveling supporting rollers in the technical field of welding. The method includes the following steps of firstly, removing fatigue layers and cracks on the surfaces of the rollers; secondly, preheating the rollers to a certain temperature; thirdly, conducting welding, wherein in the welding process, working layers are welded after base layers are welded, and dehydrogenation is conducted after welding is completed; fourthly, conducting machining to polish build up welding layers. The method has the advantages that the rollers which lose efficacy are processed through ordinary flux-coated wires, the specific build up welding method and specific build up welding conditions, cost is low, the method is simple and easy to implement, the roller surface hardness of the rollers repaired through the method is between HS66.7 and HS69.8, the hardness uniformity is + / -HS1.55 and is superior than that of new rollers, the service life of the repaired rollers is equivalent with that of the new rollers, the repaired rollers completely meet use conditions, the rollers which lose efficacy are used again, cost is saved, and economization use value of metallurgy waste of the type is improved.

Description

technical field [0001] The invention relates to the field of welding technology, in particular to a surfacing method for repairing cold-rolled leveling support rolls. Background technique [0002] The cold-rolled leveling backup roll is a key part of the skin-leveling unit, which mainly adjusts the mechanical properties of the strip, eliminates the yield plateau and slight surface defects, and is an important metallurgical spare part. During the rolling process, the back-up rolls are on the machine for 15-20 days each time, and are subjected to additional stress caused by irregular wear, roll bending force, rolling impact, etc. The working conditions are very harsh, and the main failure forms are wear and peeling. [0003] For cold-rolled leveling backup rolls, only two or three domestic enterprises such as First Heavy Machinery Group have the ability to manufacture leveling backup rolls. The material generally adopts high-carbon or high-alloy materials such as 70Cr2Mn2MoV,...

AI Technical Summary

Problems solved by technology

When the cold-rolled leveling backup roll fails, because of its high C content and high alloying elements, it has a strong tendency to harden. Cold cracks are easily generated during the surfacing process, and the weldability is poor. The hardness after surfacing The uniformity is not easy to guarantee, and the hardness difference of the roll body is required to be less than or equal to HRC2. Therefore, when the roll fails, all iron and steel enterprises scrap it directly and do not repair it for use.

[0004] During the use of cold-rolled leveling backup rolls, most of them cannot be used because the working layer is ground to the limit size, but their matrix is ​​good, and some of them fail due to local peeling and loss of a small amount of working layer. If they are directly scrapped, it will cause waste of resources and lead to steel mills. The consumption of rolls remains high and production costs rise, so it is necessary to study a welding method for repairing rolls

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