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Hitoshi soyama

Hitoshi soyama

Tohoku University, Japan

Title: Surface mechanics design of metallic materials by cavitation peening


Biography: Hitoshi soyama


Cavitation normally causes damage in hydraulic machineries such as pumps and screw propellers, as severe impacts are produced at cavitation collapses. However, cavitation impacts can be utilized for surface mechanics design for improvement of fatigue strength in the same way of shot peening. The peening method using cavitation impacts is named as “cavitation peening”. The advantage of cavitation peening is that the increase of surface roughness is small comparing with conventional shot peening, as shots are not required in cavitation peening. In order to mitigate stress corrosion cracking, introduction of compressive residual using cavitation impact was proposed [1], and it has been applied for nuclear power plants [2]. By enhancing cavitation impacts, improvement of fatigue strength was demonstrated [3]-[8]. Figure 1 shows the aspect of cavitation peening of gear by using a submerged water jet with cavitation, i.e., a cavitating jet. In order to investigate mechanism of improvement of fatigue strength, a special fatigue tester was developed to investigate crack propagation in surface modified layer [9]. Cavitation peening also suppress hydrogen embrittlement [10]. At laser peening, it is believed that impact caused by laser abrasion produces plastic deformation for surface treatment [11]. However, a bubble is generated after laser abrasion, and it produces impact at bubble collapse like cavitation, then it can be called as laser cavitation [12]. As shown in Fig. 2, when the impact passing through the material was measured, the impact induced by laser abrasion is larger than that of laser abrasion.  Namely, at submerged laser peening, peening effect would be improved by considering the laser cavitation. In the presentation, the principal of cavitation peening is introduced with applications of cavitation peening such as improvement of fatigue strength and suppression of hydrogen embrittlement.

The work was partly supported by Osawa Scientific Studies Grants Foundation. 

Recent Publications :

  1. Soyama H, Yamauchi Y, Ikohagi T, Oba R, Sato K, Shindo T, Oshima R (1996) Marked Peening Effects by Highspeed Submerged-Water-Jets - Residual Stress Change on SUS304, Jet Flow Engineering, 13 (1): 25-32.
  2. Saitou N, Enomoto K, Kurosawa K, Morinaka R, Hayashi E, Ishikwa T, Yoshimura T (2003) Development of Water Jet Peening Technique for Reactor Internal Components of Nuclear Power Plant, Jet Flow Engineering, 20 (1): 4-12.
  3. Soyama H, Kusaka T, Saka M (2001) Peening by the Use of Cavitation Impacts for the Improvement of Fatigue Strength, Journal of Materials Science Letters, 20: 1263-1265.
  4. Seki M, Soyama H, Fujii M., Yoshida A (2008) Rolling Contact Fatigue Life of Cavitation-Peened Steel Gear, Tribology Online, 3: 116-121.
  5. Soyama H, Sekine Y (2010) Sustainable Surface Modification Using Cavitation Impact for Enhancing Fatigue Strength Demonstrated by a Power Circulating-Type Gear Tester, International Journal of Sustainable Engineering, 3: 25-32.
  6. Soyama H, Takeo F (2016) Comparison between Cavitation Peening and Shot Peening for Extending the Fatigue Life of a Duralumin Plate with a Hole, Journal of Materials Processing Technology, 227: 80-87.
  7. Sato M, Takakuwa O, Nakai M, Niinomi M, Takeo F, Soyama H (2016) Using Cavitation Peening to Improve the Fatigue Life of Titanium Alloy Ti-6Al-4V Manufactured by Electron Beam Melting, Materials Sciences and Applications, 7: 181-191.
  8. Takakuwa O, Nakai M, Narita K, Niinomi M, Hasegawa K, Soyama H (2016) Enhancing the Durability of Spinal Implant Fixture Applications Made of Ti-6Al-4V ELI by Means of Cavitation Peening, International Journal of Fatigue, 92: 360-367.
  9. Soyama H (2014) Evaluation of Crack Initiation and Propagation of Stainless Steel Treated by Cavitating Peening Using a Load Controlled Plate Bending Fatigue Tester. Metal Finishing News, 15 (4): 60-62.
  10. Takakuwa O, Soyama H (2012) Suppression of Hydrogen-Assisted Fatigue Crack Growth in Austenitic Stainless Steel by Cavitation Peening, International Journal of Hydrogen Energy, 37: 5268-5276.
  11. Sasoh A, Watanabe K, Sano Y, Mukai N (2005) Behavior of Bubbles Induced by the Interaction of a Laser Pulse with a Metal Plate in Water, Applied Physics A, 80: 1497-1500.
  12. Soyama H, Sasaki H, Endo S, Iga Y (2015) Mechanical Surface Treatment of Duralumin Plate by Bubble Induced by Pulse Laser. Journal of Physics: Conference Series, 656: 012108, 1-4.