New observations on built-up edge structures for improving machining performance during the cutting of superduplex stainless steel

This work features a comprehensive investigation of built-up edge (BUE) formation during machining of superduplex stainless steel (SDSS), grade UNS S32750. To visually investigate BUE formation during the machining test, a detailed examination of BUE structures obtained at different cutting speeds was performed. The BUE geometries were determined by scanning electron microscope (SEM) and 3D white light interferometry. In addition, various BUE adhesion patterns were analyzed through electron backscatter diffraction (EBSD) and nano-indentation methods. The examined BUE revealed a high level of grain refinement and elongation for both ferrite and austenite structures, as well as a tool protection effect at specific cutting speeds. Finally, the influence of BUE on the machining process in terms of chip formation and surface integrity was studied in detail. Considerable improvements could be made to the frictional conditions and workpiece surface integrity at low cutting speeds.