The Effect of Ultrasonic Nanocrystalline Surface Modification on the High-Frequency Fretting Wear Behavior of AISI304 Steel

Abstract

The fact that one of fundamental characteristics of fretting is the very small sliding amplitude dictates the unique feature of wear mechanism. Ultrasonic Nanocrystalline Surface Modification (UNSM) technology was applied in order to investigate its effect on the high-frequency fretting wear behavior of AISI304 steel. Its influence on the fretting wear is also reported in this paper with these treated and untreated samples. UNSM delivers force onto the workpiece surface 20,000 times per second with 1,000 to 4,000 contact counts per square millimeter. UNSM creates homogenous nanocrystalline structures as well on the surface. UNSM process is expected to eliminate or significantly retard the formation of fretting wear. Nanocrystalline structure generation after UNSM has been reported to produce its unique structure and to offer a variety of beneficial properties compared to conventionally treated materials. A deformed layer of 220 microm exhibits high dislocation density, where top layer transformed to a nanostructure of the grain size in 23 nm and mechanical twins were observed. Deformation-induced martensite was observed to form at the intersections of mechanical twins, whose volume fraction has increased up to 38.4% and wear loss rate at 800,000 cycles has decreased by 40%. In this paper, experimental results are discussed to elucidate potential mechanism of high-frequency fretting wear.

Ultrasonic Nanocrystal Surface Modification Technology

“…[1][2][3][4][5][6][7][8][9][10][11][12] Previous studies confirmed that a radical improvement in the friction and wear of SAE52100 bearing steel that was subjected to UNSM treatment. [12][13][14][15] The main idea in the application of the UNSM technology to improve the RCF and rotary bending fatigue (RBF) strength of slim bearing rings is to treat not only the raceway but also the opposite side of the raceway-the outer and inner sides of both rings. The primary objective of this research is to improve the RCF and RBF strengths of slim bearings via UNSM treatment.…”