Influence of Work Hardening on the Surface of Backup Rolls for a 4-High Rolling Mill Fractured during Rolling Campaign

• Published in: Materials Vol. 15; no. 10; p. 3524
• Main Authors: Servin-Castañeda, Rumualdo, Arreola-Villa, Sixtos Antonio, Perez-Alvarado, Alejandro, Calderón-Ramos, Ismael, Torres-Gonzalez, Ruben, Martinez-Hurtado, Alonso
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 13.05.2022; MDPI
• Subjects: Analysis; backup roll; Backup rolls; Crack propagation; Cracking (fracturing); Failure analysis; Fatigue; Fatigue failure; Fatigue testing machines; Finite element method; fracture; Fracture mechanics; Hardness; Hot rolling; Inspection; Materials; Mechanical components; mechanical contact; Mechanical tests; Metal fatigue; Methods; Pressure distribution; Roll forming (Metalwork); Rolling (Metalwork); Rolling mills; Spalling; Stress concentration; Work hardening; Work rolls; Mexico; United States > US; work hardening; spalling; backup roll; mechanical contact; fracture
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma15103524

Backup rolls are the main tool in a four-high rolling mill; the rolling forces applied in load cells promote the fatigue of the material due to mechanical contact between backup rolls and work rolls. This work investigated the causes of recurrent failures in backup rolls, with cracking always initiated on the surface of the roll body and finishing in the main radius between neck and roll body. Aiming to find the causes of failure, visual inspection and morphology of the fracture were performed, complemented with mechanical tests of hardness on the stress concentration area, in addition to validating the results by applying the finite element method, using ANSYS Mechanical Static Structural Software. It was concluded that the fatigue crack initiated on the surface of BUR due to work hardening continued growing up over the fatigued material, creating beach marks, and finally, a fracture occurred in the main radius of BUR due to stress concentration. The work hardening is the main cause of spalling on BURs and other mechanical components exposed to mechanical contact.