MICROSTRUCTURE AND MECHANICAL-PROPERTIES OF RAPIDLY SOLIDIFIED DEPOSITED LAYERS OF FE-C-CR ALLOYS PRODUCED BY LOW-PRESSURE PLASMA SPRAYING

Six kinds of FeCCr alloy powder containing 1.5-3.8wt.% C and 10.7-39.1wt.% Cr were plasma sprayed on steel substrates in a low pressure chamber and rapidly solidified deposited layers were produced. When the substrates were water cooled during spraying, the constituents of the deposited layers are predominantly retained austenite, which is supersaturated with alloying elements, in alloys with low carbon and low chromium contents, and are mainly a metastable phase and metastable cementite in alloys containing high carbon and high chromium. The layer deposited on substrates which had not been water cooled are composed of the stable phases of ferrite and M7C3 and/or M23C6 (M ≡ Fe, Cr). These deposited layers have a lower hardness but a higher tensile strength compared with the layers which were deposited on water-cooled substrates. This is because, in the case of non-water-cooled substrates, the temperature rise in the layers makes the adhesion between flattened particles stronger and also produces fewer pores. © 1990.