Enhancement of the hardness of lotus-type porous copper by shot peening

Shigeki Koriyama, Paiboon Sae-Tae, Shinsuke Suzuki, Motoo Asakawa, Takuya Ide, Hideo Nakajima

Research output: Chapter in Book/Report/Conference proceedingConference contribution

4 Citations (Scopus)


Shot peening process was done on the surfaces of lotus copper plates, which were cut from the lotus copper slabs (with porosity of 37 and 48%) so that the thickness direction was parallel to the pore growth direction and the pores appeared on the surface. Some pores were closed by plastic deformation of the copper near the surface during the shot peening. The number of closed pores increased as peening time increased. Almost all the pores were closed after peening time of 40 s in the specimens of the both porosity of 37 and 48%. The closed pores were covered with a newly formed nonporous skin layer with about 200 μm in thickness. Moreover, the microstructure was fine- grained to the submicron scale in the surface layer with thickness of about 40 μm. The mechanical properties of lotus copper such as Vickers hardness, tensile strength, and bending strength were improved after shot peening. The increment of the mechanical properties was larger than that of nonporous copper. From these results, it became clear that shot peening process can form a work hardened and fine-grained nonporous skin layer on the surface of lotus metal plate. Therefore, shot peening process is considered to be an effective method for the enhancement of mechanical properties of lotus metals with maintaining porous structure.

Original languageEnglish
Title of host publicationProceedings of the 14th International Conference on Metal Forming, METAL FORMING 2012
PublisherWiley-VCH Verlag
Number of pages4
ISBN (Print)9783514007970
Publication statusPublished - 2012
Event14th International Conference on Metal Forming, METAL FORMING 2012 - Krakow, Poland
Duration: 2012 Sept 162012 Sept 19


Conference14th International Conference on Metal Forming, METAL FORMING 2012


  • Bending strength
  • Copper
  • Hardness
  • Lotus-type porous metal
  • Porous metal
  • Shot peening
  • Tensile strength

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry


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