Manufacturing method for scale breaking tension leveler working roll

Abstract

The invention discloses a manufacturing method for a scale breaking tension leveler working roll. By adopting Cr12MoVCo die steel as the material, the manufacturing method includes the steps of: rough turning, hardening and tempering, semi-finish turning, shaping treatment, coarse grinding of roll surface, preheating, medium frequency spray quenching, isothermal treatment, tempering, and finish machining, thus obtaining a finished product. Specifically, the preheating temperature is 400-450DEG C, the medium frequency spray quenching temperature is 1100-1200DEG C, the isothermal temperature is 200-250DEG C, and the tempering temperature is 500-550DEG C. In the invention, by changing the thermal treatment process, under the circumstance of obtaining quenched martensite on the surface, a transition layer is mainly based on bainite, high hardness and high wear resistance of the surface are retained, toughness of the transition layer and the core is increased, the occurrence of microcracking is reduced, and the fracture risk in use is avoided. The thickness of the transition layer is increased, the overall strength of the roll is increased, the stress distribution is more reasonable, and the grinding performance of the roll is improved.

Description

technical field [0001] The invention relates to work rolls, in particular to a method for manufacturing work rolls of a scale breaking and leveling machine. Background technique [0002] There is scale on the surface of the hot-rolled steel strip. In order to ensure the quality of the subsequent pickling process and improve the efficiency of pickling, the surface of the strip steel is often mechanically descaled before entering the pickling tank. , so that the oxide film on the surface of the strip falls off or breaks. The work rolls of the pickling line scale breaking and leveling machine are subjected to heavy force and serious wear during operation. Not only the surface is required to have high hardness and wear resistance, but also the core is required to have good toughness, otherwise there will be a risk of roll breakage. At present, the working rolls of the pickling line scale breaking and leveling machines commonly used in major steel mills are made of GCr15 materia...

AI Technical Summary

Problems solved by technology

Using the conventional manufacturing method "rough turning - quenching and tempering - semi-finishing turning - shaping treatment - rough grinding roll surface - intermediate frequency quenching (water spray cooling) - low temperature tempering - finishing to finished product" to produce the work roll of the scale breaking and straightening machine, but Since Cr12MoVCo high-carbon high-chromium die steel is hard and brittle, and has excellent hardenability, it is only suitable for use in the case of overall hardening. There are three problems in the above quenching process of Cr12MoVCo: 1. Quenching water cooling will produce a large number of microcracks , so that the roll is brittle; 2. Quenching water cooling will produce a large quenching deformation, which is easy to cause straightening fracture; 3. The grinding performance of the low-temperature tempered roll is extremely poor, and it is very easy to cause grinding cracks

Although the work rolls of the scale breaking and leveling machine produced by integral quenching can meet the requirements of high surface hardness and wear resistance, they cannot meet the toughness requirements of the core, and there is a risk of roll breakage during use

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