23.6.2005 Pressing & Sintering

Machining of Chromium Alloyed PM Steels

Powder Metallurgy (PM) is a near net shape process. Since this process is “near net”, secondary operations, e.g. machining, are often required for many applications, in order to create shapes not possible to achieve through compaction only, or to reach demanded tolerances. The use of chromium alloyed PM steels, a high strength PM material, has increased in recent time. One of the features of the chromium alloyed PM steel material is the excellent hardenability. Machinability is related to the hardness of the component. To maintain the cost benefit for PM applications, machining of such parts is to be taken into account in material selection. Guidelines for tool choice, cutting data and the effect from additives are needed to improve the machining performance of chromium alloyed PM steels in their various applications. This paper describes the machinability of a high strength chromium alloyed PM steel. Optimal settings of inserts are established at which properties like life time and surface roughness are improved. The gains achieved when machining these PM steels by using machinability additives are also shown.