TABLE OF CONTENTS The requirements for stainless steels have aesthetic (colour and shine) and technical reasons and, therefore, are broader compared to low alloyed structural steels. They are:
corrosion and oxidation resistance,
mechanical properties, e.g. ductility,
hot strength,
wear resistance,
magnetic and antimagnetic properties,
hardenability,
machinability.
In principle, the machinability of stainless steel parts cannot be as good as that of those parts with a lower alloy content due to high contents of alloying elements up to 30%, mainly of chromium and nickel. This feature is well known also from machining of wrought stainless steels, especially austenitic grades, which cause great problems due to considerable work hardening and tendency to form very long chips.
The stainless steels with their special microstructure and mechanical properties compared to conventional structural steels are used as PM material for the production of many structural parts which require secondary machining operations. Stainless steels are generally much more difficult to machine than might be expected from their low hardness which is mainly due to their high alloying with elements which deteriorated also the machinability of low alloyed structural steels.
Powder metallurgy procedures are used for producing austenitic chromium-nickel steels ( e.g. AISI 304 and 316), ferritic chromium ( e.g. AISI 430) and martensitic steels ( e.g. AISI 410). The preparation of duplex stainless steels is of great interest for research and, consequently, their machinability should also be an interesting subject. The compressibility of stainless steel powder mixtures is rather low due to...
