Analysis of Mode‡UCrack Growth Behavior in Spalling Failure of Backup Roll
Yoshihiro OHKOMORI, Chu SAKAE and Yukitaka MURAKAMI
Abstract:The crack in spalling failure of steel making backup rolls propagates mostly in Mode‡U. Mode‡Ucrack growth ratei‡™KII-da/dNjand Mode‡U threshold stress intensity factor rangei‡™KIIthj for a backup roll steel were measured by using the newly developed testing system with a conventional closed-loop type tension-compression fatigue testing machine. The Mode‡Ufatigue crack fracture surface morphology of the specimen was very similar to that of an actual backup roll. The crack growth behavior of the fractured backup roll was investigated based on fracture mechanics by using the laboratory test data of ‡™KIIth for the backup roll steel. Key Words:Spalling, Backup roll, Mode‡Ufatigue crack growth, Mode‡Uthreshold stress intensity factor range, Fracture mechanics, Fatigue, Stress intensity factor