Roll failure caused by rolling process and raw material quality, roll technology

During rolling, the cold roll is subjected to strong internal and external forces such as rolling pressure, bending moment, and shear stress, resulting in cracks in the roll and peeling of the working surface, 

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and the welds, inclusions, and edge cracks of the rolled parts can easily lead to instantaneous high temperatures, resulting in Accelerated wear and fatigue failure of rolls. Therefore, the rolling process and the quality of raw materials have a significant impact on the service life of the roll.

(1) The degree of cold work hardening of stainless steel is relatively high. As the amount of deformation increases, the strength of the rolled piece increases rapidly, and the rolling force increases. When the total reduction is 67.5%, the tensile strength of the rolled piece is as high as 2000 MPa. When the local stress of the roll exceeds the limit of the strength of the roll material, it will cause plastic deformation of the roll and then form cracks. With the action of the alternating stress, the crack propagation causes the roll to peel off or break the roll.

(2) The rolling tension control fluctuates greatly or slipping causes the belt to break, so that the roll surface contacts the broken belt, and is subjected to the combined effects of local overload thermal shock, temperature rise, and sliding friction, which causes different degrees of burns on the roll surface, resulting in the roll surface Flaking.

(3) Serious wedge shape or uneven hardness in the width direction of the raw material leads to the difference in rolling force between the operating side of the rolling mill and the transmission side or local overload thermal shock during the continuous rolling process, causing the pressure on the side with greater rolling force to exceed the strength limit of the roll material. The stress is concentrated, the edge of the roll is crushed and peeled off, or the surface of the roll is peeled off due to overload thermal shock at the position with higher hardness.

(4) Raw material inclusions, edge cracks and poor weld quality lead to strip breakage during the continuous rolling process, and thermal shock causes the roll surface to stick to steel, crack or peel off.

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