Influence of the Mn content on the kinetics of austempering transformation in compacted graphite cast iron
Moessbauer spectroscopy has been used to monitor the kinetics of austempering transformation in two compacted graphite (CG) cast irons alloyed with 0.11 and 0.58 wt pct of Mn, respectively. The phase relations were analyzed in terms of the Johnson-Mehl's equation, determining the kinetics parameters n (time exponent) and k (constant rate of the transformation). The values obtained were n = 1.4 and k = 7.47 x 10{sup {minus}3} s{sup {minus}1} for the low-Mn alloy, and n = 2.2 and k = 3.9 x 10{sup {minus}3} s{sup {minus}1} for the high-Mn alloy. These results, which reveal a faster kinetics for the low-Mn alloy, are coherent with metallographic observations, and the driving force obtained through the determination of the austenite carbon concentration that was determined from the Moessbauer data using the Genins model for the Fe-C configurations in the fcc lattice. The kinetics parameters are further compared to those obtained in austempered ductile iron (ADI), by analyzing the graphite morphology influence on the austempering transformation.
- Research Organization:
- U.N.L.P., LaPlata (AR)
- OSTI ID:
- 20001717
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 30, Issue 11; Other Information: PBD: Nov 1999
- Country of Publication:
- United States
- Language:
- English
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