Wear Behavior of Cu–Zn Alloy by Ultrasonic Nanocrystalline Surface Modification

Abstract

The ultrasonic nanocrystalline surface modification (UNSM) was applied to disk specimens made of Cu-Zn alloy in order to investigate the UNSM effects under five various conditions on wear of deformation twinning. In this paper, ball-on-disk test was conducted, and the results of UNSM-treated specimens showed that surface layer dislocation density and multi-directional twins were abruptly increased, and the grain size was altered into nano scale. UNSM delivers force onto the workpiece surface 20,000 times per second with 1,000 to 4,000 contact counts per square millimeter. The UNSM technology creates nanocrystalline and deformation twinning on the workpiece surface. One of the main concepts of this study is that defined phenomena of the UNSM technology, and the results revealed that nanocrystalline and deformation twinning depth might be controlled by means of impact energy of UNSM technology. EBSD and TEM analyses showed that deformation layer was increased up to 268 microm, and initial twin density was 0.001 x 10(6) cm(-2) and increased up to 0.343 x 10(6) cm(-2). Wear volume loss was also decreased from 703 x 10(3) mm3 to 387 x 10(3) mm3. Wear behavior according to deformation depth was observed under three different combinations. This is related to deformation depth which was created by UNSM technology.

Gigacycle Fatigue Behavior by Ultrasonic Nanocrystalline Surface Modification

“…Various severe plastic deformation methods have been developed, such as equal-channel angular pressing (ECAP) 2 3 high-pressure torsion (HPT), 2 slide loading (SL), 4 surface mechanical attrition treatment (SMAT) 5 6 and UNSM. 7 In fact that most failures of materials occur on their surfaces, such as fatigue fracture, fretting fatigue and wear, wear and corrosion; thus optimization of the surface microstructure and properties may effectively enhance the global behavior and particularly the service life of materials.…”

Effect of ultrasonic nano‐crystalline surface modification on the microstructural evolution and mechanical properties of Al5052 alloy

“…UNSM (whose parameters are listed in Table ) was applied on a 1‐cm‐thick plate of Al5052, whose chemical composition is 2.2–2.8 wt% of Mg, 0.15–0.35 wt% of Cr, 0.4% of Fe, 0.25 wt% of Si and 0.1 wt% of Cu, Mn and Zn, respectively. In short, a WC ball attached to an ultrasonic device strikes the surface of a work piece 20,000 times/s or more with 1,000 to 100,000 shots/mm 2 …”

“…Shot peening is mainly used to increase the fatigue life and stress corrosion. Ultrasonic nano‐crystalline surface modification (UNSM) is one of popular shot peening techniques for the extension of fatigue life and resistivity of stress corrosion of materials, which has been applied successfully to various metals …”

Ultrasonic Nanocrystal Surface Modification Technology

“…The detailed description of this technology was described elsewhere. 7 Strikes, which can also be described as micro cold forging, cause severe plastic and elastic deformation on the surface layers and thus, induce a nanocrystalline structure and deep compressive residual stress. 9 These strikes also produce controllable micro-dimples on the top surface of the specimen, which improves the tribological characteristics of the interacting surfaces in relative motion.…”

“…relative motion. [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.…”