Microstructures and machinability of the Inconel 182 overlays at different overlay thickness deposited by shield metal arc welding

Abstract

Nuclear steam turbines are well-known working in saturated wet-steam environment. The use of anti-corrosion material depositing or coating on the critical components and then machining to the required thickness with specific surface quality can be an effective and economical way to prevent critical components of steam turbines from corrosion and erosion. Inconel 182 can be this anti-corrosion material; however, a few literature has reported its machinability, not to mention its machinability at different overlay thickness. The objective of this study is to investigate the influence of the coated overlay thickness on microstructures and machinability of Inconel 182 overlays. First, the micro-hardness and microstructures of Inconel 182 overlays at different overlay thickness are studied. Afterwards, cutting forces, cutting temperature, surface roughness and the machined surface morphology at different overlay thickness are discussed. Finally, the prediction model for machining Inconel 182 overlays at different overlay thickness is established. The results indicate that the microstructures of Inconel 182 overlays strongly rely on overlays thickness and Inconel 182 electrode diameter (3.2 mm). The prediction model illustrates that the machinability of Inconel 182 overlays is acceptable at overlay thickness from about 0 to 2.1 mm; it is poor at overlay thickness from about 2.1 to 6.4 mm, and it is stable at overlay thickness from about 6.4 to 10 mm.