Reason for roller fracture
1、 Brittle fracture, the fracture surface of this type of rolling mill is relatively flat, and the surface layer of the roller body around the fracture surface is relatively uniform;
2、 Resilient fracture, the fracture surface of this type of rolling mill is shaped like a mushroom head, and the roller body around the fracture surface is also broken into a fragmented state.。

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After checking the two, it was found that the roller breakage method in this roller breakage accident was ductile fracture. Both brittle fracture and ductile fracture are caused by the stress of the rolling mill exceeding the core strength.

The reason for its formation is related to the residual stress of the rolling mill itself, the mechanical stress during cold rolling, and the thermal stress of the rolling mill, especially when the temperature difference between the surface of the rolling mill body and the core is large. This temperature difference is likely caused by poor roller cooling, interrupted cooling, or overheating of the roller surface at the beginning of a new cold rolling cycle. The large temperature difference between the surface and core of the rolling mill results in significant thermal stress. When the thermal stress, mechanical stress, and residual stress of the rolling mill exceed the core strength of the rolling mill, it can cause the rolling mill to break. For example, when the temperature difference between the surface and core of the rolling mill is 70 ℃, the longitudinal thermal stress of the rolling mill will also increase by 100MPa. The higher the temperature difference, the higher the increased thermal stress. Compared with rolling rolls that produce ductile fracture surfaces, the core material of rolling rolls that produce ductile fracture surfaces has stronger toughness and is less prone to fracture.