Abstract
This study is concerned with a correlation between the microstructure and fracture behavior of two AISI 4340 steels which were vacuum induction melted and then deoxidized with aluminum and titanium additions. This allowed a comparison between microstructures that underwent large increases in grain size and those that did not. When the steels were tempered at 350°C,K Ic and Charpy impact energy plots showed troughs which indicated tempered martensite embrittlement (TME). The TME results of plane strain fracture toughness are interpreted using a simple ductile fracture initiation model based on large strain deformation fields ahead of cracks, suggesting thatK Icscales roughly with the square root of the spacing of cementite particles precipitated during the tempering treatment. The trough in Charpy impact energy is found to coincide well with the amount of intergranular fracture and the effect of segregation of phosphorus on the austenite grain boundaries. In addition, cementite particles are of primary importance in initiating the intergranular cracks and, consequently, reducing the Charpy energy. These findings suggest that TME in the two 4340 steels studied can be explained quantitatively using different fracture models.
Similar content being viewed by others
References
J. N. Robinson and C. W. Tuck:Eng. Frac., Mech., 1972, vol. 4, pp. 377–93.
E. R. Parker and V. F. Zackay:Eng. Frac. Mech., 1975, vol. 7, pp. 371–75.
R. O. Ritchie, B. Francis, and W. L. Server:Metall. Trans. A, 1976, vol. 7A, pp. 831–38.
K-H. Schwalbe and W. Backfish:Fracture 1977-ICF4, D.M. R. Taplin, ed., University of Waterloo Press, Waterloo, ON Canada, 1977, vol. 2. pp. 73–78.
K-H. Schwalbe:Eng. Frac. Mech., 1977, vol. 9, pp 795–832.
F. Zia-Ebrahimi and G. Krauss:Acta Metall., 1984, vol. 10, pp. 1767–77.
S. Lee, L. Majno, and R. J. Asaro:Metall. Trans. A, 1985, vol. 16A, pp. 1633–48.
Y. C. Chi, S. Lee, K. Cho, and J. Duffy: Brown University Technical Report, ARO Grant DAAL-03-88-K-0015, no. 2, Aug. 1988.
S. K. Banerji, C. J. McMahon, Jr., and H. C. Feng:Metall. Trans. A, 1978, vol. 9A, pp. 237–47.
C. L. Briant and S. K. Banerji:Int. Metals Rev. 1978, no. 4, pp. 164–99.
C. L. Briant and S. K. Banerji:Metall. Trans. A, 1982 vol. 13A, pp. 827–36.
N. Bandyopadhyay and C. J. McMahon, Jr.:Metall. Trans. A, 1983, vol. 14A, pp. 1313–25.
G. Thomas:Metall. Trans. A, 1978, vol. 9A, pp. 439–50.
C. N. Sastry and W. E. WoodMater. Sci. and Eng., 1980, vol. 45, pp. 277–80.
M. Sarikaya, B. G. Steinberg, and G. Thomas:Metall. Trans. A, 1982, vol. 13A, pp. 2227–37.
M. Sarikaya, A. K. Jhingan, and G. Thomas:Metall. Trans. A, 1983, vol. 14A, pp. 1121–33.
M. F. Carlson, B. V. Narasimha, and G. Thomas:Metall. Trans. A, 1979, vol. 10A, pp. 1273–84.
J. P. Materkowski and G. Krauss:Metall. Trans. A, 1979, vol. 10A, pp. 1743–51.
S. Lee:Scripta Metall., 1988, vol. 22, pp. 59–64.
H. Couque, R. J. Asaro, J. Duffy, and S. H. Lee:Metall. Trans. A, 1988, vol. 19A, pp. 2179–206.
F. Zia-Ebrahimi, D. K. Matlock, and G. Krauss:Scripta Metall., 1982, vol. 16, pp. 987–92.
F. Zia-Ebrahimi and G. Krauss:Metall. Trans. A, 1983, vol. 14A, pp. 1109–19.
D. Y. Lee and H. L. Marcus: inMetallurgical Treatises, T. K. Tien and J. F. Elliott, eds., TMS-AIME, Warrendale, PA, 1981, pp. 571–87.
R. M. McMeeking:Trans. ASME, Oct. 1977, pp. 290–97.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lee, S., Lee, D.Y. & Asaro, R.J. Correlation of microstructure and tempered martensite embrittlement in two 4340 steels. Metall Trans A 20, 1089–1103 (1989). https://doi.org/10.1007/BF02650144
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02650144