Machinability and Chip Morphology Study of Inconel 740H and Haynes 282 for Advanced-Ultra Supercritical Applications

Abstract

Abstract: High speed machining of Nickel based alloys has gained a lot of research interest since the last decade owing to their applications in areas like power generation, aerospace, marine propulsion, and nuclear reactors. For the realization of an advanced ultra-supercritical (A-USC) thermal plant, operating at service temperatures of about 700 to 760oC and pressures of around 24 MPa, the use of Nickel-based super alloys is indispensable. Some these parts used for the application may be required to be machined before use, although the machinability of these materials is relatively poor. Chip morphological studies are performed for better understanding of cutting force and surface finish of the alloys. In this work, authors have tried to study the effect of machining parameters like cutting speed, feed rate, rake angle, and nose radius on chip morphology like peak height, valley height, tooth height, tooth pitch, and segmentation frequency. The results of chip morphology studies indicate the need for saw tooth chips for better machining. Accordingly, Inconel 740H is found to have better machinability than Haynes 282 for the used range of machining parameters. Moreover, higher cutting speeds, lower feed rates, and positive rake angles are found to yield optimum conditions for an improved machinability