MICROSTRUCTURAL RESPONSE OF INCONEL 690 SUPER ALLOYS TO ARTIFICIAL AGEING
Keywords:
Ageing, Inconel 690, hardness, microstructureAbstract
Modern manufacturing processes require materials possessing properties that can be used for applications like turbines, heat exchangers, condensers etc. One such material is the Inconel 690 bearing various properties like high strength at elevated temperature, toughness, resistance to degradation in corrosive or oxidizing environment, etc. The present work is mainly focused on the study of hardness of Inconel 690 in As Forged condition and at ageing conditions of 725°C for 4 hours respectively. The As Forging is done by hot working the Inconel alloy at 1200°C for delivering high strength and resisting hot deformation. Also SEM (Scanning Electron Microscope) analyses of both the specimens are being conducted in order to analyze and understand the effect of ageing. The hardness measurement for the aged specimen was done on a Rockwell hardness testing machine on a B scale after air cooling of the specimen to room temperature. The experiments showed that the hardness of the Inconel alloy decreased from 82 HRB to 59 HRB (Rockwell B Hardness) after being subjected to heat treatment and ageing. From the morphology of the aged specimen it was observed that, there is formation of large grain boundaries in the same grain directions and also drastic increase in the grain size which relieved the internal stresses due to ageing.
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