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A study on Cavity Closure Behavior During Hot Open Die Forging Process

열간 자유단조 공정시 내부 공극 압착 거동에 관한 연구

  • 권용철 (한국기계연구원 부설 재료연구소 소재성형연구센터) ;
  • 이정환 (한국기계연구원 부설 재료연구소 소재성형연구센터) ;
  • 이승욱 (포스코특수강(주) 기술연구소) ;
  • 정용수 (포스코특수강(주) 기술연구소) ;
  • 김남수 (포스코특수강(주) 기술연구소) ;
  • 이영선 (한국기계연구원 부설 재료연구소 소재성형연구센터)
  • Published : 2007.07.01

Abstract

Recently, there is a need to produce a large forged part for the flight, shipping, some energies, and military industries, etc. Therefore, an open die forging technique of cast ingots is required to obtain higher quality of large size forged parts. Cogging process is one of the primary stages in many open die forging processes. In the cogging process prior to some open die forging processes, internal cavities have to be eliminated for defect-free. The present work is concerned with the elimination of the internal cavities in large ingots so as to obtain sound products. In this study, hot compression tests were carried out to obtain the flow stress of cast microstructure at different temperature and strain rates. The FEM analysis is performed to investigate the overlap defect of cast ingots during cogging stage. The measured flow stress data were used to simulate the cogging process of cast ingot using the practical material properties. Also the analysis of cavity closure is performed by using the $DEFORM^{TM}-3D$. The calculated results of cavity closure behavior are compared with the measured results before and after cogging, which are scanned by the X-ray scanner. From this result, the criteria for deformation amounts effect on the cavity closure can be investigated by the comparison between practical experiment and numerical analysis.

Keywords

References

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  1. Study on Manufacturing Process of Hollow Main Shaft by Open Die Forging vol.40, pp.2, 2016, https://doi.org/10.3795/KSME-A.2016.40.2.221
  2. Comparative Study on Pore Closing in Open Die Forging by Conventional Forging Press and Radial Forging Machine vol.19, pp.7, 2010, https://doi.org/10.5228/KSTP.2010.19.7.399
  3. A Study on the mold attachment for process automation with hot open die forging vol.16, pp.5, 2012, https://doi.org/10.9726/kspse.2012.16.5.070