Abstract
Changes in the creep resistance and dislocation substructure with addition of carbon have been studied in the temperature range between 900-1050°C, by using high purity Ni-20Cr alloys containing carbon up to 0.032wt%.The creep resistance of the alloy increased at the temperatures less than 1 000°C, with increasing of carbon content dissolved in γ-matrix. Such a strengthening effect was presumed to be caused by solid solution of carbon, and was associated with increase in dislocation density within subgrains. At 1050°C, the formation of subgrains or the dynamic recrystallization took place in the alloy with 0.032wt% carbon and these microstructural changes brought the decrease in the creep resistance of the alloy. The precipitation of carbide (M7C3) at the grain boundaries significantly increased the creep resistance, and this phenomenon was very similar to the grain boundary precipitation strengthening effect by α2-W phase in Ni-Cr-W alloys.
