| Summary: | The precipitation and recrystallization behaviour of austenitic stainless steels containing niobium has been studied by electron microscopy and hardness measurements. The precipitation of NbC has been investigated in steels containing 20% Cr/25% Ni/0.8% Nb with carbon contents of 0.01% and 0.1% respectively. After water-quenching from 1300°C and ageing in the range 700 - 850°C, the low carbon steel showed mainly precipitation on unextended dislocations while in the high carbon alloy, stacking fault precipitation was predominant. The activation energy for the precipitation process was found to be consistent with the rate controlling process being niobium diffusion. Direct quenching to the ageing temperature was found to reduce matrix precipitation. Prior deformation of 1% and 5% after solution treatment accelerated stacking fault formation, and increasing the deformation to 10% resulted in precipitation of NbC on dislocations with no stacking fault type precipitation.
|
|---|
