Influence of heat treatment on the mechanical and tribological properties of Incoloy 800H Superalloy

The selection and use of high strength alloys with high wear resistance (at room and high temperature) are mandatory in aerospace, nuclear, automotive, petroleum, space, furnace, and chemical industries in which Incoloy 800H superalloy is the right choice. However, this alloy is under the class of 'difficult to cut material' caused by their significant properties. In the present work, the heat treatment on Incoloy 800H superalloy was carried out at 1075 degrees C for 60 min and then the samples were cooled in the air (air cooling, AC) and furnace (furnace cooling, FC) to modify the microstructure. The mechanical and tribological behavior were examined on the heat-treated samples at room temperature to eliminate the effect of dynamic strain aging (DSA) which usually occurs at elevated temperatures in superalloys. Hardness measurement and compression tests were carried out to examine the variation of strength. Further, the dry sliding wear tests at room temperature were performed to analyze wear resistance of heat-treated specimens and compared with the as-received (AR) sample. Besides, the wear mechanism and surface roughness of worn-out specimens were analyzed. The result indicates that the air-cooled (AC) sample possessed high hardness, high compression strength, and more resistance to wear as compared to AR and FC samples. The identified wear mechanisms in AR and FC samples were abrasive, deep grooves, plastic deformation while the AC specimen exhibits mild grooves and lesser debris particles. Fractography analysis was also performed to find the nature or mode of fractures on the samples. ANOVA result indicates that the sample hardness after heat treatment has the most influencing parameter followed by the applied load on the wear rate and the coefficient of friction (CoF). The measured average roughness of the AC specimen has shown lesser value than the AR and FC specimens due to refined grain structure.