Influence of plastic deformation and prolonged ageing time on microstructure of a Haynes 242 alloy.
The material used in this study was a commercial HAYNES alloy 242 with a nominal composition of Ni-25% Mo-8% Cr (in wt.%). In the standard heat treatment, the 242 alloy is annealed at a temperature between 1065 and 1095 degrees C and then water quenched. The ageing treatment is carried out at 650 degrees C for 24 h in order to develop the long-range-order strengthening. The alloy in the conventionally aged condition was additionally cold rolled to 50% reduction in thickness and subsequently subjected to prolonged ageing at 650 degrees C for 4000 h. The enhanced diffusion resulted in the decomposition of the Ni(2)(Mo,Cr) metastable phase into the stable Ni(3)Mo-based phase. The presence of the new stable phase increased the yield and tensile strengths but deteriorated the ductility of the alloy at both room and 650 degrees C temperatures.
Dymek
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AGH University of Science and Technology, 30-059 Kraków, Al. Mickiewicza 30, Poland. dymek@galaxy.uci.agh.edu.pl
Wróbel
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Dollar
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Blicharski
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