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Amanov, Auezhan,Karimbaev, Ruslan,Maleki, Erfan,Unal, Okan,Pyun, Young-Sik,Amanov, Tileubay Elsevier 2019 Surface & coatings technology Vol.358 No.-
<P><B>Abstract</B></P> <P>In this study, the fatigue performance of AISI 304 subjected to shot peening (SP), ultrasonic nanocrystal surface modification (UNSM) and the combination of SP + UNSM processes was systematically assessed by rotary bending fatigue (RBF) tester at different stress levels. The purpose of combining SP and UNSM processes is to find out whether SP following UNSM process can further improve the fatigue life of AISI 304 in comparison with the SP and UNSM processes alone. Interestingly, the fatigue strength of AISI 304 was deteriorated by the combination of SP + UNSM processes in comparison with the UNSM process alone, but the combination of SP + UNSM processes demonstrated a higher fatigue strength in comparison with the SP process alone.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SP, UNSM and SP + UNSM processes were applied to AISI 304. </LI> <LI> UNSM process exhibited the highest surface hardness. </LI> <LI> UNSM process induced the highest compressive residual stress. </LI> <LI> SP + UNSM process exhibited better results than SP process. </LI> <LI> UNSM process demonstrated the longest fatigue life than SP and SP + UNSM processes. </LI> </UL> </P>
Low friction and high strength of 316L stainless steel tubing for biomedical applications
Amanov, Auezhan,Lee, Soo–,Wohn,Pyun, Young–,Sik Elsevier 2017 Materials Science and Engineering C Vol.71 No.-
<P>We propose herein a nondestructive surface modification technique called ultrasonic nanocrystalline surface modification (UNSM) to increase the strength and to improve the tribological performance of 316L stainless steel (SS) tubing. Nanocrystallization along nearly the complete tube thickness of 200 pm was achieved by UNSM technique that was confirmed by electron backscatter diffraction (EBSD). Nano-hardness of the untreated and UNSM-treated specimens was measured using a nanoindentation. Results revealed that a substantial increase in hardness was obtained for the UNSM-treated specimen that may be attributed to the nanocrystallization and refined grains. Stress-straip behavior of the untreated and UNSM-treated specimens was assessed by a 3-point bending test. It was found that the UNSM-treated specimen exhibited a much higher strength than that of the untreated specimen. In addition, the tribological behavior of the untreated and UNSM-treated specimens with an outer diameter (OD) of 1.6 mm and an inner diameter (ID) of 1.2 mm was investigated using a cylinder-on-cylinder (crossed tubes of equal radius) tribo-tester against itself under dry conditions at ambient temperature. The friction coefficient and wear resistance of the UNSM-treated specimen were remarkably improved compared to that of the untreated specimen. The significant increase in hardness after UNSM treatment is responsible for the improved friction coefficient and wear resistance of the tubing. Thus, the UNSM technique was found to be beneficial to improving the mechanical and tribological properties of 316L SS tubing for various potential biomedical applications, in particular for coronary artery stents. (C) 2016 Elsevier B.V. All rights reserved.</P>
Amanov, A.,Sasaki, S.,Cho, I.S.,Suzuki, Y.,Kim, H.J.,Kim, D.E. Scientific and Technical Press ; Elsevier Science 2013 Materials & design Vol.47 No.-
In this work, the friction and wear behavior of Fe-Ni-Cr alloy specimens processed by direct metal laser sintering (DMLS) method was investigated by using a ball-on-disk reciprocating tribotester sliding against a hardened steel ball under dry sliding conditions. After DMLS, the specimens were further treated by hot isostatic pressing (HIP) in order to reduce the porosity and to increase the density. Subsequently, one of the specimens was subjected to high-frequency ultrasonic peening (HFUP) with the aim to enhance the tribological properties. The microstructural characterization was conducted using a scanning electron microscope (SEM) and an atomic force microscope (AFM). In addition, nano-scratch tests were carried out on the specimens using a nano-scratch testing (NST) system. The friction and nano-scratch tests results showed that the HFUP-treated specimen led to a reduction in friction coefficient and wear rate, and an increase in resistance to scratch compared to that of the HFUP-free specimen, which may be attributed to the increase in hardness and the formation of corrugated structure.
Improvement in Fretting Wear Damage of Annealed Inconel 718 Alloy at a Temperature of 200 °C
Amanov, Auezhan,Kim, Jun-Hyong,Pyun, Young-Sik American Scientific Publishers 2016 Journal of nanoscience and nanotechnology Vol.16 No.12
<P>In this study, a nanocrystalline surface layer with a thickness of about 50 mu m was produced at the top surface of annealed Inconel 718 alloy by ultrasonic nanocrystalline surface modification (UNSM) technique. The presence of nanocrystalline structure and plastically deformed layer at the top surface were characterized by electron backscatter diffraction (EBSD) and scanning electron microscopy (SEM), respectively. The hardness of the specimens before and after UNSM treatment was measured using a micro-hardness tester at a load of 300 gf for dwell time of 30 s. The effectiveness of produced nanocrystalline surface layeron the fretting wear damage was investigated at a temperature of 200 degrees C under dry fretting conditions against SAE52100 bearing steel. Results revealed that the UNSM treatment enhanced the fretting wear resistance of annealed Inconel 718 alloy compared to the untreated specimen, which may be attributed to the presence of nanocrystalline structure and deformed layer, induced compressive residual stress and increased hardness. In addition, a fretting wear mechanism of the untreated and UNSM-treated specimens was discussed.</P>
Amanov, A.,Umarov, R. Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.441 No.-
<P><B>Abstract</B></P> <P>In this study, a combination of local heat treatment (LHT) with (w/) and without (w/o) ultrasonic nanocrystal surface modification (UNSM) technique was applied to Inconel 690 alloy at room and high temperatures (RT and HT). The main purpose of this study is to investigate the influence of LHT w/ and w/o UNSM processing on the mechanical and fretting wear mitigation of Inconel 690 alloy. The surface roughness of the specimens was increased with increasing the LHT temperature w/ and w/o UNSM from RT to HT at 700 °C, while the surface hardness of the RT and HT at 300 °C specimens was increased and softening occurred at HT at 700 °C. The mechanical properties of the specimens were investigated using a tensile stress test. It was found that the stress-strain curve of the UNSM-treated at RT exhibited better mechanical characteristics in comparison with the as-received one. Moreover, the specimens treated at HT at 300 and 700 °C exhibited better results in terms of strain, but there was no significant difference in stress. The UNSM treated specimens at HT of 300 °C had better results in comparison with other specimens. In addition, the fretting wear resistance of those specimens was assessed using a ball-on-disk fretting wear tester at temperatures of 25 and 80 °C. The fretting wear resistance of Inconel 690 alloy was also increased by the combination of LHT + UNSM processing, which may be attributed to the increase in mechanical properties, increase in surface roughness, induced compressive residual stress and the presence of a nanostructured surface layer. Hence, Inconel 690 alloy with the increased mechanical properties and fretting wear resistance by the combination of LHT + UNSM processing could be beneficial for nuclear applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A local heat treatment along with UNSM treatment was employed to Inconel 690 alloy. </LI> <LI> The surface roughness was increased with increasing the temperature. </LI> <LI> The surface hardness was reduced at 700 °C, while it was increase at 300 °C. </LI> <LI> The fretting wear was mitigated by local heat treatment along with UNSM treatment. </LI> <LI> The role of local heat treatment and UNSM processing is significant. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Amanov, Auezhan,Pyun, Young-Sik ASME International 2016 Journal of tribology Vol.138 No.3
<P>An ultrasonic nanocrystal surface modification (UNSM) technique was applied to a thermally sprayed yttria-stabilized zirconia (YSZ) ceramic coating deposited onto a hot tool steel substrate to improve the mechanical and tribological properties. The friction test results showed that the UNSM-treated coating had a smoother surface, a lower friction, and a higher resistance to wear compared to that of the as-sprayed coating. It was also demonstrated that the UNSM technique improved the adhesion behavior of the coating by about 24%. Hence, it was found that a hybrid use of thermal spray coating (TSC) and UNSM technique is a meaningful way to bring together synergy effect of two emerging surface technologies in terms of tribology.</P>
Auezhan Amanov,편영식 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.8
This study reports the improvement in microstructural and tribological characteristics of sintered alumina (Al2O3) ceramicsubjected to ultrasonic nanocrystalline surface modification (UNSM) technique. The surface microstructure of the untreatedand UNSM-treated specimens was examined by scanning electron microscopy (SEM), laser scanning microscopy (LSM) andX-ray diffraction (XRD). The tribological properties of the specimens were assessed using a ball-on-disk tribometer against abearing steel (SAE52100) ball. It was confirmed by SEM that the UNSM-treated specimen had much denser microstructurethan that of the untreated specimen. The surface roughness of the UNSM-treated specimen obtained by AFM was found tobe smoother compared to that of the untreated specimen, which may be attributed to the decrease in porosity. The tribologicaltest results showed that the UNSM-treated specimens exhibited better tribological properties compared to those of theuntreated specimens. It was also found that the UNSM technique was able to modify the surface in the topmost surface layer. The results of this study are expected to make sintered Al2O3 ceramic more attractive for a numerous applications in variousindustries.