Transactions of Materials Processing (소성∙가공)

The Korean Society for Technology of Plasticity and materials processing (한국소성∙가공학회)
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Evaluation of Homogeneous Ultra-fine Grain Refinements via Equal Channel Angler Pressing Process

등통로각압축공정을 통한 결정립의 균질한 초미세립화에 대한 고찰

  • 김우열 (포항공과대학교(POSTECH) 신소재공학과) ;
  • 이학현 (포항공과대학교(POSTECH) 신소재공학과) ;
  • 서승재 (풍산) ;
  • 이재근 (풍산) ;
  • 윤태식 (방위산업기술지원센터, 광운대학교 방위사업학과) ;
  • 김형섭 (포항공과대학교(POSTECH) 신소재공학과)
  • Received : 2018.04.17
  • Accepted : 2018.07.12
  • Published : 2018.08.01
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Abstract

Severe plastic deformation (SPD) is a promising method for drastically enhancing the mechanical properties of the materials by grain refinement of metallic materials. However, inhomogeneous deformation during the SPD process results in the inhomogeneous microstructure of the SPD-processed material. We manufactured cylindrical copper specimens of 42 mm in diameter with ultrafine grains (UFG) using an equal channel angular pressing (ECAP) to figure out the relationship between homogeneous microstructure and the number of the processing passes. Two specimens, which are ECAP-processed 4 times (4pass) and 6 times (6pass) each with Route Bc, are prepared for comparison of mechanical properties and microstructure. The results show that the mechanical properties of the two specimens (4pass and 6pass) are similar. Moreover, both the specimens show highly enhanced mechanical properties. The 4pass specimen, however, shows inhomogeneity in hardness distribution, while the 6pass specimen shows a homogeneous distribution. Microstructure analysis reveals that the 4pass specimen has an inhomogeneous microstructure with incompletely refined grain structure. This inhomogeneity of the 4pass specimen could be explained by the circumferential rotation during ECAP process.

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References

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