Surface Roughness, Topography, Accuracy, Chip Formation Analysis & Investigation of M390 and M398 Steels after Hard Machining

Article deals with processing of intermetallic materials produced by powder metallurgy M390 and M398 Microclean (R) produced by Bohler. Main interest is the analysis & measurement of their surface roughness and topography after the processing by DNMG and WNMG geometry of cutting inserts with 0.4 and 0.8 mm radius after hard turning at the same process parameters for both materials and all types of cutting inserts. The comparative studies were carried out for the microgeometrical and chip formation research on the machined surfaces and the technological processes were assessed, including chip diagrams. Spectral analysis was used to verify the composition of investigated materials by spectral analysis measuring device. In order to examine the surfaces in detail, in addition to the standard roughness measurement, surface topography was performed by the coherent correlation interferometric microscope. The results of surface roughness as well as topography show higher wear resistance of M398 material compared to M390. This was confirmed indirectly by the fact that it is primarily shown by the higher surface roughness of M398 after machining under the same conditions. These properties are obtained by a higher content of additive elements, respectively of their carbides. Based on the conclusions of these experiments, additional knowledge and recommendations for the processing of these materials were created.