Effect of ultrasonic peening technology on the thermal fatigue of rolling mill rolls

چکیده مقاله

In this study, the use of ultrasonic peening technol-ogy (UPT) on the rolling mill roll graphite steel GSH48 was surveyed in order to improve some surface mechanical and thermal properties. UPT is one of the newest technologies of severe plastic deformation in which vibratory tool strikes the workpiece s urface with continual r eciprocating motions, resulting in severe plastic deformation on the surface. This method enhances mechanical and thermal properties like fa-tigue life and thermal fatigue. Thermal fatigue in the rolling mill rolls causes the growth of crack on the surface and grow-ing that in depth leads to the break of the roll. The influence of the UPT on the improvement of thermal fatigue life of the hot-rolling rolls was investigated by conducting thermal fatigue test in which parameters were adjusted in accordance with the process of hot-rolling. By the simulation and manufacturing of peening vibratory tool, preparation of the process was accom-plished including setting up the ultrasonic vibratory tool on lathe machine. According to the standard of related devices, samples were prepared form the surface of roll and the exam-inations of fatigue, thermal fatigue, and surface topology by atomic force microscopy (AFM) were performed on work-pieces in different states before and after the UPT process with one, two, and three passes. The process of ultrasonic peening caused severe plastic deformation on surface layers and prevented from crack growth. The results of this research in-dicated the rise of the fatigue and thermal fatigue life of the pieces after UPT process.