Fe-Cr-C hardfacing alloys for high-temperature applications

The microstructure and phase chemistry of a Fe-34Cr-4.5C wt% hardfacing alloy has been investigated using transmission electron microscopy and microanalytical techniques. The microstructure is found to consist of large primary M₇C₃. carbides in a eutectic mixture of austenite and more M₇C₃. The results indicate that the microstructure of the undiluted alloy becomes configurationally frozen at a temperature of about 1150° C during deposition by the manual metal arc welding technique. This allows the metastable austenite phase to contain a large chromium concentration ( 16 to 17 wt %), thus imparting good corrosion and oxidation resistance. Experimental data on the partitioning of chromium, manganese and silicon between the carbide phases are discussed in the context of the high-temperature stability of the alloy.