Influence of striking edge radius (2 vs. 8 mm) on instrumented Charpy data and absorbed energies

Original Paper

Abstract

The most commonly used test standards for performing Charpy impact tests (ISO 148 and ASTM E 23) envisage the use of strikers having different radii of the striking edge, i.e. 2 mm (ISO) and 8 mm (ASTM). The effect of striker geometry on Charpy results was extensively studied in the past in terms of absorbed energy measured by the machine encoder, but few investigations are available on the influence of striker configuration on the results of instrumented Charpy tests (characteristic forces, displacements and integrated energy). In this paper, these effects are investigated based on the analysis of published results from three interlaboratory studies and some unpublished Charpy data obtained at SCK·CEN. The t-test was used for establishing the statistical significance of the observed effects. The instrumented variables which are the most sensitive to the radius of the striking edge are the maximum force and its corresponding displacement, with 8 mm-strikers providing systematically higher values. The effect on general yield forces, on the other hand, is less consistent and more difficult to rationalize, although 2 mm-strikers generally tend to deliver higher values. Absorbed energies, obtained both from the instrumented trace and from the pendulum encoder, are almost insensitive to the type of striker up to 200 J. For higher energy levels, the values obtained from 8 mm-strikers become progressively larger. Data scatter is generally higher for 2 mm-strikers.

Keywords

Instrumented Charpy tests Striker configuration Absorbed energy t-Test Dynamic toughness tests 

References

  1. ASTM International (2000) Pendulum impact testing: a century of progress. ASTM STP 1380 (Siewert TA, Manahan MP (eds)). ASTM International, West Conshohocken, PAGoogle Scholar
  2. ESIS (2002) From Charpy to present impact testing. In: François D, Pineau A (eds) Proceedings of the Charpy centenary conference, CCC2001, Poitiers (France), ESIS Publication 30, Elsevier, Amsterdam, 2–5 October 2001Google Scholar
  3. Fink DA (1990) Quantitative comparison and evaluation of various notch machining methods and how they affect ASTM E23 and ISO R442 testing equipment results. In: Charpy impact test: factors and variables. ASTM STP 1072. American Society for Testing and Materials, Philadelphia, pp 94–119Google Scholar
  4. Heerens J, Hellmann D (2002) Development of the Euro fracture toughness dataset. Eng Fract Mech 69(4): 421–449. doi:10.1016/S0013-7944(01)00067-4 CrossRefGoogle Scholar
  5. Lucon E (2008) Influence of striking edge radius (2 mm versus 8 mm) on instrumented Charpy data and absorbed energies. Open Report SCK·CEN BLG-1057, August 2008Google Scholar
  6. Lucon E, Viehrig H-W (2007) Round-robin exercise on instrumented impact testing of precracked Charpy specimens (IAEA Coordinated Research Program Phase 8). In: Proceedings of 2007 pressure vessels & piping conference and the eighth international conference on creep and fatigue at elevated temperatures, ASME PVP 2007/CREEP 8, San Antonio, TX, Paper PVP2007-26088, 22–26 July 2007Google Scholar
  7. Manahan MP, Martin FJ, Stonesifer RB (2000) Results of the ASTM instrumented/miniaturized round-robin test program. In: Pendulum impact testing: a century of progress. ASTM STP 1380. ASTM International, West Conshohocken, PA, pp 223–241Google Scholar
  8. McCowan CN, Pauwels J, Revise G, Nakano H (2000) International comparison of impact verification programs. In: Pendulum impact testing: a century of progress. ASTM STP 1380. ASTM International, West Conshohocken PA 73–89Google Scholar
  9. McCowan CN, Splett JD, Lucon E (2008) Dynamic force measurement: instrumented Charpy impact testing. NISTIR 6652. National Institute of Standards and Technology, Boulder COGoogle Scholar
  10. Morita S, Kobayashi T (2004) Ductile-Brittle transition behaviors with two striker geometries in the instrumented Charpy impact test. Mater Sc Forum 449–452: 861–864CrossRefGoogle Scholar
  11. Naniwa T, Shibaike M, Tanaka M, Tani H, Shiota K, Namio H, Shiraishi T (1990) Effects of the striking edge radius on the Charpy impact test. In: Charpy impact test: factors and variables. ASTM STP 1072. American Society for Testing and Materials, Philadelphia, pp 67–80Google Scholar
  12. Nanstad RK, Sokolov MA (1995) Charpy impact test results on five materials and NIST verification specimens using instrumented 2-mm and 8-mm strikers. In: Pendulum impact machines: Procedures and specimens for verification. ASTM STP 1248. American Society for Testing and Materials, Philadelphia, pp 111–139Google Scholar
  13. Revise G (1990) Influence of dimensional parameter of an impact test machine on the results of a test. In: Charpy impact test: factors and variables. ASTM STP 1072. American Society for Testing and Materials, Philadelphia, pp 35–53Google Scholar
  14. Ruth EA (1995) Striker geometry and its effect on absorbed energy. In: Pendulum impact machines: procedures and specimens for verification. ASTM STP 1248. American Society for Testing and Materials, Philadelphia, pp 101–110Google Scholar
  15. Schuurmans J, Scibetta M, Lucon E, Puzzolante J-L (2008) Influence of strain gage position on the static and dynamic performance of instrumented impact strikers. J Test Eval (accepted)Google Scholar
  16. Siewert TA, Vigliotti DP (1995) The effect of Charpy V-notch striker radii on the absorbed energy. In: Pendulum Impact Machines: Procedures and Specimens for Verification. ASTM STP 1248. American Society for Testing and Materials, Philadelphia, pp 140–152Google Scholar
  17. Siewert TA, Manahan MP, McCowan CN, Holt JM, Marsh FJ, Ruth EA (2000) The history and importance of impact testing. In: Pendulum impact testing: a century of progress. ASTM STP 1380. ASTM International, West Conshohocken, PA, pp 3–16Google Scholar
  18. Tanaka M, Ohno Y, Horigome H, Tani H, Shiota K, Misawa A (1995) Effects of the striking edge radius and asymmetrical strikes on Charpy impact test results. In: Pendulum impact machines: procedures and specimens for verification. ASTM STP 1248. American Society for Testing and Materials, Philadelphia, pp 153–167Google Scholar
  19. Towers OL (1983) Effects of striker geometry on Charpy results. Metab Constr 15(11): 682–686Google Scholar
  20. Viehrig H-W, Lucon E (2007) IAEA coordinated research project on master curve approach to monitor fracture toughness of RPV steels: effect of loading rate. In: Proceedings of 2007 pressure vessels & piping conference and the eighth international conference on creep and fatigue at elevated temperatures, ASME PVP 2007/CREEP 8, San Antonio, TX, Paper PVP2007–26087, 22–26 July 2007Google Scholar

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  1. 1.SCK·CEN, Institute for Nuclear Material ScienceMolBelgium

Personalised recommendations