A comparative tribological study on as-cast and heat-treated Inconel-718 superalloy at elevated temperature

The application of Inconel-718 ranges from structural components to engine parts such as turbine blades and compressor discs. Inconel-718 is an age-hardenable alloy. We are presenting a comparative tribological study on as-cast and heat-treated Inconel-718 superalloy. The wear behavior of both as-cast and aged Inconel-718 alloy was investigated using a linear reciprocating tribometer at 25 degrees C, 225 degrees C, and 450 degrees C against Si 3 N 4 ball. The heat treatment of Inconel-718 alloy resulted in the improvement of the hardness of the alloy. All the tribological tests were conducted under a constant 20 N normal load. The observed coefficient of friction was found to be decreasing with the increase in temperature. The wear tracks were characterized by a three-dimensional optical profilometer and scanning electron microscopy (SEM). The observed wear volume loss (mm 3 ) of the aged alloy was less than that of the as-cast Inconel-718 alloy. SEM of the worn sample reveals that the main operating wear mechanism at 25 degrees C is delamination whereas at elevated temperatures of 225 degrees C and 450 degrees C, the main operating wear mechanism is abrasion, adhesion, oxidation and spalling. SEM of the counter-surface was also conducted in order to understand the adhesion on its surface and it was found that the adhered oxide contained mainly Ni and Nb oxides.