The Influence of Austempering Heat Treatment Variables on Dimensional Changes of a Ni-Cu Ductile Iron

Abstract:

Control and prediction of the dimensional changes (DC) during austempering heat treatment of ductile iron is difficult because many factors influence this behavior. In the present work cylindrical specimens of ductile iron were used to study the effect of austenitizing temperature, austempering time, temperature, and prior microstructure on DC. The results show that DC increases with increasing austenitizing temperature in the range of 850 to 950°C with a fully ausferrite microstructure. Evaluation of different combinations of ferrite and pearlite contents in prior microstructure indicates that a fully ferritic structure has the highest DC. In addition, results show that by lowering austempering temperature from 400 to 250°C, DC increases.

• Periodical: Materials Science Forum (Volumes 514-516)
• Pages: 702-706
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.514-516.702
• Online since: May 2006
• Authors: Sasan Yazdani
• Keywords: Austempered Ductile Iron, Austempering, Dimensional Changes

References

[1] R.C. Voigt, C.R. Loper Jr, J. Heat Treating, 3, (4), Dec. 1984, p.291.

[2] M. Grech and J.M. Young, Mat. Sci. Tech., 6, (5), 1990, p.415.

[3] H.L. Morgan, Br. Foundryman 80, (2), 1987, p.98.

[4] O.J. Moncada, J.A. Sikora, AFS Trans., Vol. 104, Apr. 1996, p.577.

[5] M. Zarinejad et al., Second national surface engineering seminar, Isfahan, Iran, 1996, p.91.

[6] M. Nili, M. Zarinejad, Advances in industrial materials, 1998, 95.

[7] J.R. Keough, 1991 World Conference on ADI, Vol. II, BL., Illinois, USA, Mar. 1991, p.638.

[8] Unpublished work in Sahand University of Technology, Tabriz, Iran.

[9] Annual Book of ASTM Standards, Vol. 03 . 01, 1990, p.753.

[10] B.D. Cullity, Elements of X-Ray Diffr., Addison Wesely, 2nd Ed., (1978).

[11] S. Yazdani, R. Elliott, Mat. Sci. and Tech., Vol. 15, May 1999, p.531.

[12] S. Yazdani, R. Elliott, Mat. Sci. and Tech., Vol. 15, May 1999, p.541.

[13] F. Neumann, Recent Research in Cast Iron, Gordon and Beach, 1965, p.659.

[14] K.B. Rundman, R.C. Klug, AFS Transactions, 1982, p.499.

[15] M. Peet et al, Scripta Materialia, Vol. 50, 2004, p.1277.

[16] H.T. Angus, Cast iron: Physical and Engineering Properties., Second Ed., 1976. 1 1. 2 1. 4 1. 6 1. 8 2 1 10 100 1000 Austempering time (min) Austenite carbon content (%) Figure 7. The variation of austenite carbon content with austempering time after austenitizing at 900°C for austempering temperature 400°C. 0 0. 05 0. 1 0. 15 0. 2 0. 25 0. 3 0. 35 0. 4 0 20 40 60 80 100 Volume of ferrite (%) DC (%) 250 375 Figure 8. The variation of dimensional changes with volume fraction of ferrite after austenitizing at 900°C for austempering temperatures 250 and 375°C.

DOI: 10.1016/0025-5416(87)90556-8