New short time face turning method for testing the machinability of PM steels

The production of sintered structural components by powder metallurgy (PM) route is basically done by uniaxial cold pressing of metal powders in closed dies followed by sintering at temperatures in the range of 1120–1300 °C in H/N atmospheres (solid phase sintering). The machinability of PM steels is tested by different methods for the various cutting processes. Compared to wrought steels, PM steels exist in an almost unlimited variety of microstructures. This fact complicates creation of a uniform solution for testing and characterizing the problems in machinability of PM steels. Simple and easy methods can be appropriate as a first approach to the machining problem especially for industrial practice and for the research. The short time face turning method using common small ring-shaped specimens as test pieces is presented here as a new method for testing the machinability of PM steels. The method was tested on Fe–C and Distaloy type materials. The critical number of cutting passes up to a tool flank wear of VB = 0.3 mm, critical time, critical volume of removed material, surface finish and morphology of the chips were the criteria for checking the technical effectivity of the method applied. The results attained show that the face turning test method used here is simple and easy and can fulfil many requirements for assessing the machinability of PM steels in turning.