A Study on Hardness and Effective Strain of Cold-Worken Products

냉간 가공 제품의 경도와 유효 변형률에 관한 연구

  • 최영 (인제대학교 수송기계부품기술혁신센터) ;
  • 박준홍 (부산대학교 기계기술연구소)
  • Published : 2004.09.01


It is already known that hardness number of cold-forged product is in close conjunction with its effective strain. This paper presents the method to predict the relation between effective strains and hardness by using FE-simulation of hardness test from the conception that hardness indicates resistance to plastic deformation. The results of FE-simulation for the materials are compared with those of experiments and also compared with those of experiments in reference to show the feasibility of the proposed method. In addition, the present method was applied to the cold-forged product to verify the relation between hardness and effective strain. As a result, the predicted hardness number by the present method is in good agreement with experimental values. Prediction of hardness fur a cold-forged product comes to be possible by estimating the relation between effective strain and hardness using the proposed method in this study.


  1. Dieter, G. E., Mechanical Metallurgy, McGraw-Hill, 1986
  2. Kim, H. K., Lee, S. M. andAltan, T., 'Prediction of Hardness Distribution in Cold Backward Extruded Cups,' J. of Mater. Process. Technol. Vol. 59, pp. 113-121, 1996 https://doi.org/10.1016/0924-0136(96)02292-3
  3. Hartley, P., Strugess, C. E. N. and Rowe, G. W., 'Prediction of deformation and homogeneity in rim-disc forging,' J. of Mechanical Working Technology, Vol. 4, pp. 145-154, 1980 https://doi.org/10.1016/0378-3804(80)90032-7
  4. Kudo, H., Sato, K. and Aoi, K., 'On Cold Forgrability Test,' Annals of CIRP, Vol. 16, pp. 309-318, 1967
  5. Lee, C. H., 'An Experimental Study on the Relation between Flow Stress and Vickers Hardness,' Spring Proc. of KSTP 97, pp. 65-68, 1997
  6. Lee, C. H., 'A Study on the Theoretical Relation between Flow Stress and Vickers Hardness,' Spring Proc. of KSTP 97, pp. 69-72, 1997
  7. Wilhelm, 'Investigation on the relation between Vickers hardness and equivalent strain for cold forming process,' Berichte aus dem Institut fr Umformtechnik, Universitt Stuttgart, No. 9, Essen, Girardet, 1969
  8. Shiozaki, T. and Kawasaki, T., 'Flow stress and ductility in carbon steels for cold forging,' J. of the JSTP, Vol. 27, pp. 568-572, 1986
  9. Lee, S. M., Kim, H., Shivpuri, R. and Altan, T., 'Estimation of Hardness Distribution for Cold Forged Parts by the Finite Element Method,' Autumn Proc. of KSTP 93, pp. 56-62, 1993
  10. ASTM E140-84, Standard Hardness Conversion Tables for Metals
  11. Smithells, Metals Reference Book (Sixth ed.)
  12. ASTM E10-84, Standard Test Method for Brinell Hardness of Metallic Materials
  13. Choi, J. C., Choi, Y., Tak, S. J., 'The Forging of Helical Gears (I): Experiments and Upper-Bound Analysis,' International Journal of Mechanical Sciences, Vol. 40, No. 4, pp. 325, 1998 https://doi.org/10.1016/S0020-7403(97)00032-5
  14. Choi, J. C. and Choi, Y., 'Precision Forging of Spur Gears with Inside Relief,' International Journal of Machine Tools and Manufacture, Vol. 39, No. 10, pp. 1575, 1999 https://doi.org/10.1016/S0890-6955(99)00015-2
  15. Yeo, H. T., Choi, Y. and Hur, K. D., 'Stress Analysis of the Prestressed Dies by Using FEM,' Journal of the Korean Society of Precision Engineering, Vol. 16, No. 6, pp. 114-122, 1999
  16. Cho, H. Y., Hur, J. H. and Min, K. S., 'Development of Automated Forging Design System for Forging Process Design of Stepped Asymmetric Parts,' Journal of the Korean Society of Precision Engineering, Vol. 17, No. 3, pp. 102-107, 2000