Estimation of Creep Crack Growth Properties Using Circumferential Notched Round Bar Specimen for 12CrWCoB Rotor Steel

Abstract:

Most heat resisting materials in structural components are used under multi-axial stress conditions and under such conditions ductile materials often exhibit brittle manner and low creep ductility at elevated temperature. Creep crack initiation and growth properties are also affected by multi-axial stress and it is important to evaluate these effects when laboratory data are applied to structural components. Creep crack growth tests using circumferential notched round bar specimens are a simple method to investigate multi-axial stress effects without using complicated test facilities. Creep crack growth tests have been performed using a 12CrWCoB turbine rotor steel. In order to investigate the effects of multi-axial stress on creep crack growth properties, the tests were conducted for various notch depths at 650°C. The circumferential notched round bar specimen showed brittle crack growth behaviour under multi-axial stress conditions. Creep crack growth rate was characterized in terms of the C* parameter. A 12CrWCoB turbine rotor steel has been tested using circumferential notched round bar specimens with different multi-axiality. Circumferential notched round bar specimens show increased brittle creep crack growth behaviour due to the multi-axial stress condition. Creep crack growth properties could be predicted by allowing for the decrease of creep ductility under multi-axial conditions.

• Periodical: Key Engineering Materials (Volumes 297-300)
• Pages: 397-402
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.297-300.397
• Online since: November 2005
• Authors: Je Chang Ha, Joon Hyun Lee, Masaaki Tabuchi, A.Toshimitsu Yokobori Jr.
• Keywords: C* Parameter, Circumferential Notched Round Bar Specimen, Creep Crack Growth, Creep Ductility, Multi-Axial Stress Condition

References

[1] ASTM. Standard test method for measurement of creep crack growth rate in metals. ASTM-E1457-92 (1992).

[2] ASTM, Standard test method for measurement of creep crack growth rate in metals. ASTM-E1457-00 (2000).

[3] K.H. Schwalbe, R.A. Ainsworth, A. Saxena and T. Yokobori: Engng Fract Mech Vol. 62 (1) (1999), pp.123-142.

[4] T. Yokobori: Strength and fracture of materials, in Japanese (Gihodo, Tokyo 1999).

[5] H. Riedel: Fracture at high temperatures, Berlin: Springer (1987).

[6] G.A. Webster and R.A. Ainsworth: High temperature component life assessment (Chapman and Hall, London 1994).

[7] T. Yokobori: Strength of materials, 2nd Ed., in Japanese (Iwanami, Tokyo 1974) pp.110-111.

[8] H.H. Johnson: Materials Research and Standards Vol. 5 (9) (1965), pp.442-445.

[9] T. Adachi, A.T. Yokobori Jr., M. Tabuchi, A. Fuji and T. Yokobori: Proceedings of 10th Int. Conf. on Fracture, Honolulu: Elsevier Science (2001).

[10] JSME Mechanical Engineers' Handbook. Fundamentals A4, Strength of Materials, Tokyo: JSME (1984) p.107.

[11] K. Ohji, K. Ogura and S. Kubo: Trans Jpn. Soc. Mech. Engr. Vol. 44 (1978), pp.1831-1838.

[12] J.C. Ha, M. Tabuchi, H. Hongo, A.T. Yokobori Jr. and A. Fuji: International Journal of Pressure Vessels and Piping Vol. 81 (2004), pp.403-404.

DOI: 10.1016/j.ijpvp.2004.03.011

[13] M. Tabuchi, T. Adachi, A.T. Yokobori Jr., A. Fuji, J.C. Ha and T. Yokobori: International Journal of Pressure Vessels and Piping Vol. 80 (2003), pp.420-421.

DOI: 10.1016/s0308-0161(03)00096-6