Abstract
Four point bending (4PB) tests of notched specimens and COD tests of precracked specimens were carried out on two steels; one steel was treated into two groups with the same ferrite grain size but different carbide sizes, the other steel with different ferrite grain sizes but similar carbide sizes. The results of the tests show that the toughness measured in notched specimens is mainly determined by the grain sizes, which define the local fracture stress σf; the size of carbide particle plays a minor role. However, on the contrary, in precracked specimens the toughness is sensitive to the carbide sizes, which affect the critical plastic strain εpc for initiating a crack nucleus; the effect of grain size is indistinct. By these inferences the behavioral discrepancy of large grain steel in improvement of crack fracture toughness while reducing the notch toughness is explained.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Chen, J.H., Zhu, L. and Ma, H. (1990). On The scattering of local fracture stress ? f. Acta Metallurgica and Materialia 38, 2527–2535.
Chen, J.H. and Wang, G.Z. (1992). Study of mechanism of cleavage fracture at low temperature. Metallurgical Transactions 23A, 509–517.
Chen, J.H. and Yan, C. (1992). Comparison of toughness of C-Mn weld steel with different grain sizes. Metallurgical Transactions 23A, 2549–2556.
Chen, J.H., Zhu, L., Wang, G.Z. and Wang, Z. (1993). Further Investigation of critical events in cleavage fracture in C-Mn base and weld Steel. Metallurgical Transactions 24A, 659–667.
Chen, J.H., Yan, C. and Sun, J. (1994). Further study of the mechanism of cleavage fracture at low temperatures. Acta Metallurgica and Materialia 42, 251–261.
Chen, J.H., Wang, G.Z., Yan, C., Ma, H. and Zhu, L. (1997a). Advances in the mechanism of cleavage fracture of low alloy steel at low temperatures. Part I: Critical event. International Journal of Fracture 83, 105–120.
Chen, J.H., Wang, G.Z., Yan, C., Ma, H. and Zhu, L. (1997b). Advances in the mechanism of cleavage fracture of low alloy steel at low temperature Part III. Local fracture stress ? f. International Journal of Fracture 83, 139–157.
Chen, J.H., Hu, S.H. and Wang, G.Z. (2001). Mechanism of detrimental effects of carbon content on cleavage fracture toughness of low-alloy steel. Metallurgical Transactions 32A, 1081–1091.
Chen, J.H., Wang, G.Z. and Wang, Q. (2002). Change of critical events of scleavage fracture with variation of microscopic features of low-alloy steels. Metallurgical and Materials Transactions 33A, 3393–3402.
Chen, J.H., Li, Z. and Wang, G.Z. (2003a). Effects of tensile prestrain on the notch toughness of Low-alloy steel. Metallurgical Transactions 34A, 1055–1068.
Chen, J.H., Wang, Q., Wang, G.Z. and Li, Z. (2003b). Fracture behavior at crack tip-a new framework for cleavage mechanism of steel, Acta Materialia 51, 1841–1855.
Griffiths, J.R and Owen, D.R.J. (1971). Elastic-plastic stress analysis for a notched bar in plane strain bending. Journal of Mechanics and Physics of Solids 19, 419–431.
Knott, J.F. (1973). Fundaments of Fracture Mechanics. Butterworth, London.
Lewandowski, J.J. and Thompson, A.W. (1986). Microstructural effects on the cleavage fracture-stress of fully pearlitic eutectoid steel. Metallurgical Transactions 17A, 1769–1786.
Lewandowski, J.J. and Thompson, A.W. (1987). Micromechanisms of cleavage fracture in fully pearlitic microstructures. Acta Metallurgica and Materialia 35, 1453–1462.
Lin, T., Evans, A.G. and Ritchie, R.O. (1987). Stochastic modeling of the independent roles of particle size and grain size in transgranular cleavage fracture. Metallurgical Transactions 18A, 641–651.
Miyata, T., Yang, R.C., Otsuka, A., Haze, T. and Ahira, S. (1989). Cleavage fracture of steels with fine grained ferrite, coarse grained bainitic and martensitic microstructures. Advances in Fracture Research, Proceeding of ICF7, (Edited by K. Salama, K. Ravi-Chander, R. Taplin, and P. Rama Rao), Pergamon Press, Oxford, 2563–2571.
Rice, J.R and Johnson, M.A. (1970). Inelastic Behavior of Solids, pp. 641–670, (Edited by M.F. Kanninen, W.F.Adler, A.R. Rosenfield and R.I. Jaffe), McGraw-Hill, New York.
Ritchie, R.O., Francis, B. and Server, W.L. (1976). Evaluation of toughness in aisi 4340 alloy-steel austenitized at low and high-temperatures. Metallurgical Transactions 7A, 831–838.
Ritchie, R.O. and Horn, R.M. (1978). Further considerations on inconsistency in toughness evaluation of aisi 4340 steel austenitized at increasing temperatures. Metallurgical Transactions 9A, 331–341.
Samant, A.V. and Lewandowski, J.J. (1997a). Effects of test temperature, grain size, and alloy additions on the cleavage fracture stress of polycrystalline niobium. Metallurgical Transactions 28A, 389–399.
Samant, A.V. and Lewandowski, J.J. (1997b). Effects of test temperature, grain size, and alloy additions on the low-temperature fracture toughness of polycrystalline niobium. Metallurgical Transactions 28A, 2297–2307.
Wang, G.Z. and Chen, J.H. (1996). A comparison of fracture behavior of low alloy steels with different sizes of carbide particles. Metallurgical and Materials Transactions 27A, 1909–1917.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Chen, J., Wang, G., Wang, Q. et al. Effects of sizes of ferrite grains and carbide particles on toughness of notched and precracked specimens of low-alloy steels. International Journal of Fracture 126, 223–241 (2004). https://doi.org/10.1023/B:FRAC.0000026545.74317.4c
Issue Date:
DOI: https://doi.org/10.1023/B:FRAC.0000026545.74317.4c