Effect of thermal and thermomechanical ageing on the microstructure and mechanical properties of a Ni-Cr alloy

Thermal ageing experiments at 850 and 950 degrees C for 1000 h with and without an applied stress have been applied to INCONEL 617 alloy. The consequences of these treatments characterized in terms of microstructure evolution and the tensile behavior have been studied at room and elevated temperatures. It is shown that thermal ageing strongly reduces the ductility of the alloy at room temperature, whereas the saturation stress measured at elevated temperature is only slightly affected. Applying a small stress of 7MPa during thermal ageing has negligible effects on the tensile behavior.