Journal of Mechanical Science and Technology

The Korean Society of Mechanical Engineers (대한기계학회)
권호 표지

Evaluation of Fracture Strength and Material Degradation for Weldment of High Temperature Service Steel Using Advanced Small Punch Test

  • Lee, Dong-Hwan (Division of Mechanical ＆ Aerospace System Engineering, Chonbuk National University)
  • Published : 2004.09.01
Download PDF
⟨ Previous Next ⟩

Abstract

This paper presents an effective and reliable evaluation method for fracture strength and material degradation of the micro-structure of high temperature service steel weldment using advanced small punch (ASP) test developed from conventional small punch (CSP) test. For the purpose of the ASP test, a lower die with a minimized ${\Phi}$1.5 mm diameter loading ball and an optimized deformation guide hole of ${\Phi}$3 mm diameter were designed. The behaviors of fracture energy (E$\_$sp/), ductile-brittle transition temperature (DBTT) and material degradation from the ASP test showed a definite dependency on the micro-structure of weldment. Results obtained from ASP test were compared and reviewed with results from CSP test, Charpy impact test, and hardness test. The utility and reliability of the proposed ASP test were verified by investigating fracture strength, behavior of DBTT, and fracture location of each micro-structure of steel weldment for test specimen in ASP test. It was observed that the fracture toughness in the micro-structure of FL＋CGHAZ and ICHAZ decreased remarkably with increasing aging time. From studies of all micro-structures, it was observed that FGHAZ microstructure has the most excellent fracture toughness, and it showed absence of material degradation.

Keywords

References

  1. Abel-Latif, A. M., Corbett, J. M., Sidney D. and Taplin, D. M. R., 1981, 'Effects of Microstructural Degradation on Creep Life Prediction of 2.25Cr-1Mo Steel,' Proc. of the 5th International Conference on Fracture, Cannes, France, Vol. 4, pp. 1613-1620
  2. Baik, J. M., Kameda, J. and Buck, O., 1986, 'Development of Small punch Tests for Ductile- Brittle Transition Temperature Measurement of Temper Embrittled Ni-Cr Steels,' ASTM STP 888, pp.92-11l
  3. Chung, S. H., Takahashi, H. and Suzuki, M., 1978, 'Microstructural Gradient in HAZ and its Influence upon Toe HAZ Fracture Toughness,' Welding in the World, p. 248
  4. Haggag, F. M., Byun, T. S., Hong, J. H., Miraglia, P. Q. and Murty, K. L., 1998, 'Indentation-Energy-To-Fracture (IEF) Parameter for Characterization of DBTT in Carbon Steels Using Nondestructive Automated Ball Indentation (ABI) Technique,' Scripta Materialia, Vol. 38, No.4, pp. 645-651 https://doi.org/10.1016/S1359-6462(98)00519-3
  5. Kim, J. K., Yoon, T. Y., Song, K. W., Lee, J. J. and Chung, S. H., 1991, 'A Study of Evaluation for In-Service Material Degradation of High Temperature Structural Components by Grain Boundary Etching Method,' Transactions of the KSME A, Vol. 15, No.3, pp. 898-906
  6. Lee, D. H., Lee, S. I., Kwon, I. H., Baek, S. S and Yu, H. S., 2002, 'Fracture Strength Evaluation of Heat Resisting Steel Weldment by Advanced Small Punch Test,' Proc. KWS Welding Strength Research Workshop, pp. 76-83
  7. Liao, J., Ikeuchi, K. and Matsuda, F., 1998, 'Toughness Investigation on simulated weld HAZs of SQV-2A Pressure Vessel Steel,' Nuclear Engineering and Design, Vol. 183, pp. 9-20 https://doi.org/10.1016/S0029-5493(98)00151-4
  8. Lyu, D. Y., Chung, S. H., Lim, J. K., Jung, H. D., Tamakawa, K. and Takahashi, H., 1989, 'A Study on Fracture Strength Evaluation of Steel Welded Joint by Small Punch Test (I),' Journal of KWS, Vol. 7, No.3, pp. 28-35
  9. Nishiyama, Y., Fukuya, K., Suzuki, M. and Eto, M., 1998, 'Irradiation Embrittlement of $2{\frac{1}{4}}$ Cr-1Mo Steel at $400^{\circ}C$ and its Electrochemical Evaluation,' Journal of Nuclear Materials, 258-263, pp. 1187-1192 https://doi.org/10.1016/S0022-3115(98)00184-6
  10. Viswanathan, R., 1993, 'Damage Mechanisms and Life Assessment of High Temperature Components,' ASM International Metals Park, pp.206-208
  11. Yu, H. S., Ahn, B. G., Lyu, D. Y. and Chung, S. H., 1998, 'A Study on Fracture Toughness of Welded Joint and Orientation in TMCP Steel by the SP Test,' Journal of KWS, Vol. 16, No.6, pp. 35-43