Correlating tool wear, surface roughness and corrosion resistance in the turning process of super duplex stainless steel

Abstract

Super duplex stainless steels are extremely corrosion-resistant alloys designed for very demanding applications that expose them to corrosive environments, such as seawater. Due to their chemical composition and microstructure, which provide high mechanical strength and thermal resistance as well as high ductility, the machinability of these alloys is generally poor, resulting in long production cycles and high tooling costs. Moreover, machining may be harmful for the corrosion resistance of the alloy. The goal of this research is to study the turning operation of UNS 32750 alloy, known commercially as SAF 2507, and its influence on the alloy’s corrosion resistance in practical applications. Tests were performed, using cutting speed and cooling conditions with low and high fluid pressure as the input variables. The results indicate that turning with PVD-coated inserts under high-pressure cooling resulted in long tool lives, good workpiece roughness and high corrosion resistance of the material after machining. The most frequent wear mechanism found during the tests was notch wear, while the main tool wear mechanism was attrition.