Nickel alloy 625 is widely used in submarine equipment for the oil and gas industry, which operate in an extremely adverse environment. In order to reduce the costs of these components, weld overlay cladding is employed. The surface generated by this process presents some irregularities that represent an additional difficulty to the machining process. The present work investigates the use of whiskers-reinforced ceramic tools and SiAlON in turning of alloy 625 clad on AISI 4130 steel by an automatic tungsten inert gas (TIG) cladding system. The results indicate the feasibility of the industrial application of the SiAlON inserts in rough turning of the alloy 625 clad, as well as the impossibility of using whiskers-reinforced ceramic tools (Al2O3 + SiCw) in the same conditions. The highest flank and notch wear of the SiAlON inserts were observed for the lowest cutting speed (140 m/min), which induced the formation of burrs in the workpiece at the depth of cut. Adhesion occurred more intensively at this condition. The least flank and notch wear were achieved by using cutting speed of 160 m/min and feed-rate of 0.25 mm/rev. Prolonged turning with worn tools resulted in microstructural alterations of the workpiece material and surface damages.
Keywords:
alloy 625; turning; tool wear; ceramic
