Surface damage of roll hot rolling

The roll is a production tool for plastic deformation of the metal. It is subject to a complex stress state during production, and it is prone to roll failure, such as peeling, fracture, and roll surface damage. Among the roll failure forms, there are many types of roll surface damage, which are also common failure forms, including roll surface cracks, indentations, oxide film shedding, slag inclusion, steel sticking, abnormal wear, etc.


1. Cracks on the surface of the roll

Cracks can be divided into normal cracks and abnormal cracks. Normal cracks, also called thermal cracks, are a micro-surface phenomenon that occurs on the roll surface due to thermal stress caused by multiple temperature cycles. Abnormal cracks are thermal shock cracks caused by slipping, sticking to steel, sticking to steel, piled up steel, flicking and other reasons during the rolling process, and cracks with certain depth and ductility are locally formed on the surface of the roll surface.


2. Indentation

It mainly refers to the foreign matter such as iron scale that is pressed in during the production process due to cleaning, resulting in continuous or discontinuous irregular pits on the roller surface.


3. Oxide film peeling off

At the beginning of rolling, after a period of blanching, a thin layer of silver-gray or light blue oxide film is formed on the surface of the roll, which is very important for protecting the surface of the roll and improving the surface quality of the rolled piece. Due to the repeated action of the rolling force, the oxide film produces microcracks around the carbide; when the cooling capacity of the roll is insufficient, it is difficult to form a dense oxide film on the surface of the roll, and even if the oxide film is formed, it will quickly deteriorate. If the rolling is unreasonable, the oxide film will be destroyed quickly during the forming process, causing the oxide film to fall off, leaving meteor spots on the roll surface, resulting in an increase in the roughness and wear of the roll surface.


4. Rebar sticking, abnormal wear, etc.

Due to abnormal rolling, the surface of the roll and the rolled piece stick together, resulting in steel sticking; the process parameters are unreasonable during rolling, resulting in excessive consumption of the roll within the same width kilometer, resulting in uneven wear of the roll surface.

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