Contribution to study and development of PM stainless steels with improved properties

Purpose: of this paper is to present the studies performed at Politecnico di Torino aimed to the development of innovative composition of PM duplex stainless steels characterized with very high and unique mechanical and corrosion resistance properties. Previously a base research to attain improvement of quality and performances of sintered AISI 316L has been developed. Moreover the possibility to enhance mechanical and corrosion resistance properties through contact infiltration or through the use of reactive sintering techniques has also been demonstrated and discussed. Design/methodology/approach: The duplex compositions have been obtained using austenitic AISI 316L and AISI 41OL as starting base powders. While AISI 316L stainless steel samples have been manufactured using different combinations of compacting pressure and sintering parameters, or a modified composition able to allow reactive sintering process, as well as the contact infiltration with bronze. Findings: The studies have been forwarded towards the static and dynamic mechanical properties, as well as the corrosion behavior. Lowering the porosity level and increasing the sintering degree, by use of higher compacting pressure or sintering temperature, is of great effectiveness, especially from the point of view of mechanical properties. Moreover, the innovative duplex composition are very promising. Practical implications: according to achieved results, duplex stainless steels can be obtained starting from austenitic of martensitic stainless steel powders by simple addition of single elements, through a process in vacuum. Concerning traditional austenitic grades, the obtained results demonstrate the benefits of contact infiltration and of reactive sintering techniques to sinter stainless steels components having higher density and better mechanical and corrosion resistance properties than the traditional compositions, compacted at high pressure and sintered at elevated temperature. Originality/value: very promising results have been obtained with special compositions able to allow the production of real duplex alloys, as well as with a modified composition of AISI 316L grade able to realize a reactive sintering process.