Effect of Fine Particle Shot Peening on Very High Cycle Fatigue Properties of Extruded Magnesium Alloys

Shiozawa, Kazuaki; Miyazaki, Masashi

doi:10.1299/kikaia.79.876

Cited by 8 publications

(3 citation statements)

References 23 publications

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“…On the other hand, as mentioned in the introduction, many useful techniques based on S 2 PD also provide a similar nanocrystallization and improve the mechanical properties. For example, the investigations regarding shot peening (Shahnewaz et al, 2012;Shiozawa and Miyazaki, 2013;Kakiuchi et al, 2016) have reported that the fatigue property improved due to the residual stress and the nanocrystalline introduced at the surface; however, the improvement effect was not obtained due to the notching effect caused by the increase in the surface roughness during the process. In contrast, in the SCP process, the change in the surface state was very limited, and it did not affect the improvement of fatigue property of the specimen due to SCP.…”

Section: Fatigue Test Results and Fracture Surface Observationsmentioning

confidence: 99%

“…Surface severe plastic deformation (S 2 PD), which is a surface treatment that uses large plastic strains, improves mechanical properties, such as hardness, fatigue strength and wear resistance, on metal surfaces by creating a nanocrystalline layer on the bulk material. Many techniques based on S 2 PD, such as surface mechanical attrition treatment (SMAT) (Lu, K. and Lu, J., 2004;Shahrezaei et al, 2019), surface mechanical grinding treatment (SMGT) (Liu et al, 2015), and shot peening (Shiozawa and Miyazaki, 2013), have recently been studied as useful processes for nanocrystallizing the surface of metal materials. Techniques used to strike workpiece surfaces using ultrasonic vibration, such as ultrasonic nanocrystal surface modification (UNSM) (Wu et al, 2014) and ultrasonic impact treatment (UIT) (Togasaki et al, 2010), have also attracted attention as useful ways to modify surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Surface modification of machine-finished magnesium alloy AZ31 using a scanning cyclic press

Fujimura

Ooga

Takahashi

et al. 2020

Mechanical Engineering Journal

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A machined material has a work-hardened layer at its surface. In this study, a surface modification technique, the scanning cyclic press (SCP), was applied to machined specimens of magnesium alloy, AZ31, to investigate whether SCP can improve its fatigue properties regardless of the surface finish. During the SCP process, a vibrating indenter reciprocally scanned the specimen's surface, and it applied cyclical low-compressive loadings to the surface for 8 × 10 6 cycles. After applying SCP, the surfaces of the specimens were observed using a laser scanning microscope, and the surface roughness was measured. The surface observation and surface roughness measurement showed that the changes in the surface state after applying SCP were relatively small and the surface roughness after applying SCP was more homogenous than before applying SCP. Uniaxial push-pull fatigue tests were conducted for SCP-treated specimens and untreated specimens. The test results showed that the fatigue life of SCP-treated specimens was longer than that of untreated specimens. To clarify the reason for the improvement effect, the fracture surfaces were observed using a scanning electron microscope (SEM). The SEM observation showed that the fracture morphology was different between the SCP-treated specimen and the untreated specimen. In the SCP-treated specimen, fatigue fracture origins were sub-surface, while the untreated specimen fractured at the surface. These results suggest that SCP could improve the fatigue properties of AZ31 regardless of the surface finish of the specimen before SCP.

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Section: Fatigue Test Results and Fracture Surface Observationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surface modification of machine-finished magnesium alloy AZ31 using a scanning cyclic press

Fujimura

Ooga

Takahashi

et al. 2020

Mechanical Engineering Journal

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“…important findings are that the nano-crystalline structure forms beneath the crack surface (Oguma, N. et al, 2003) and that a large number of compressive force applications during fatigue loading plays a crucial role in forming the structure (Hong et al, 2016) and the convex-concave fracture surface (Shiina et al, 2002, Shiina et al, 2004. This unique fracture surface has been observed not only in high-strength steel, but also in titanium , Oguma, H. et al, 2004, aluminum (Yamada and Miyakawa, 2009) and magnesium alloys (Shiozawa and Miyazaki, 2013). As a reason for the appearance of the fracture surface and the nanocrystallization beneath it, the authors have hypothesized that a huge number of repeated contacts of the crack surfaces has a similar mechanical effect as SPD (Nakamura et al, 2007, Nakamura et al, 2010, Nakamura and Oguma, 2011.…”

Section: Introductionmentioning

confidence: 98%

Nano-structural refinement of metallic surfaces by using low-compression cyclical loading

Fujimura

Nakamura

Ueno

2018

Mechanical Engineering Letters

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Recent studies on very high cycle fatigue (VHCF) have observed a unique fracture surface with a fine granular area around the crack origin that arises from long-term repeated contacts of fracture surfaces (over 10 7 cycles). A fine microstructure including nanocrystalline is known to form in the matrix just beneath the fracture surface. Focusing on these phenomena, this study devised a new surface modification technique, called Cyclic Press (CP), that creates a nanocrystalline layer using cyclic compressive loading. Repeated low-compression loadings were applied to the surfaces of SNCM439 high-strength steel and ADC12 die-cast aluminum alloy with an indenter for 5 × 10 7 cycles. Then, the surfaces and cross sections were analyzed by using a laser microscope, a scanning electron microscope, a scanning ion microscope, and energy dispersive X-ray spectrometry (EDS). As a result, a nanocrystalline structure very similar to that of the cross section beneath the fracture surface in the VHCF regime clearly formed in the surface layer of both materials. Additionally, an oxygen-rich layer formed at the surface of the CP-treated ADC12. This result was considered to be caused by diffusion of elemental oxygen in the atmosphere by a huge number of repeated contacts between the indenter and specimen. Overall, the results indicate that CP is a useful technique for forming nanocrystalline layers in metal surfaces and can also be expected as a new method for diffusing surrounding gaseous elements into surfaces at room temperature.

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Fatigue strength improvement of Mg alloy AZ61 by double ultrasonic shot peening

Kakiuchi

Uematsu

Sanada

et al. 2016

Transactions of the JSME (In Japanese)

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Rotary bending fatigue tests using magnesium alloy AZ61 treated by double ultrasonic shot peening (USP) and peening under other conditions were performed to investigate the effect of shot peening (SP) on the fatigue behavior and to obtain high and stable improvement in fatigue strength. The single USP treatment was conducted under the condition of the shot diameter of 0.6 mm, 1.0 mm and 2.0 mm and the coverage of 80 %, 200 % and 300 %. The air blast SP was conducted using Zirblast B120 shot and under the coverage of 300 %. The first treatment of the double USP was conducted under the condition of the shot diameter of 1.0 mm and the coverage of 300 %, and then the second treatment was conducted under the condition of the shot diameter of 0.6 mm and the coverage of 300 %. Microstructures, hardness, residual stress and surface roughness of each specimen were investigated and compared. The fatigue strength of USP specimens which were treated under the low coverage and the high coverage with the large shot diameter was decreased, while that of the other USP and the air SP specimens was improved. High fatigue strength improvement was achieved by the double USP compared with the base metal and the other single USP and air SP specimens. It is considered that the improvement of fatigue strength of double USP specimen is attributed to the enough increase in hardness and compressive residual stress in the first treatment and the decrease of surface roughness and the removal or the modification of the thin work-softened layer in the second treatment.

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Effect of Fine Particle Shot Peening on Very High Cycle Fatigue Properties of Extruded Magnesium Alloys

Cited by 8 publications

References 23 publications

Surface modification of machine-finished magnesium alloy AZ31 using a scanning cyclic press

Surface modification of machine-finished magnesium alloy AZ31 using a scanning cyclic press

Nano-structural refinement of metallic surfaces by using low-compression cyclical loading

Fatigue strength improvement of Mg alloy AZ61 by double ultrasonic shot peening

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