Ferrite and Carbide Mixtures in Sintered Hyper-Eutectoid Fe-xMo-0.90C Alloys

Abstract

Phase transformations in low- to medium-carbon Fe-Mo-C alloys have been widely investigated for decades and fruitful information regarding phase transformation is available. However, hyper-eutectoid Fe-Mo-C alloys were least studied. Metallurgical information regarding high-carbon Fe-Mo-C alloys is rarely available. In this work, high-carbon Fe-xMo-0.90C alloys (x = 0.50, 0.85 and 1.50 wt%) were prepared by sintering powder compacts made from pre-alloyed Fe-Mo admixed with 0.90 wt% graphite. Phase transformations in experimental sintered alloys were studied under two different cooling rates, e.g. 0.1 and 5.4 °C/s. Under the cooling rate, phase transformation products were controlled by molybdenum content. In all slowly cooled sintered alloys, phase transformations involved with eutectoid decomposition. The eutectoid transformation products, simply ferrite and carbide mixtures in the form of upper bainite, were generally observed in all slowly cooled sintered alloys. The nodular bainite and inverse bainite coexisted with upper bainite in slowly cooled sintered alloys with higher molybdenum contents. Under the fast cooling rate, fine pearlite and upper bainite were the common transformation products. In addition, in fast cooled alloys with the higher molybdenum contents, inverse bainite formed as one of the transformation products.

KEYWORDS:

• Sintering
• eutectoid transformation
• pearlite
• upper bainite
• inverse bainite

Acknowledgments

The authors are also grateful for support from National Metal and Materials Technology Center.

Additional information

Funding

The authors are grateful for financial support from National Science and Technology Development Agency (NSTDA) under the project P1951261. W. Srijampan and A. Wanalerkngam would like to thank for scholarship from TGIST (TG-33-26-60-016D and TG-MT-SUT-63-018D).