High strength sintered steels fabrication by in-situ solid solution strengthening and grain growth prevention during sintering

Due to the known Powder Metallurgy advantages of sintered structural steel parts fabrication, intensive researches are performed to overcome its known limitations concerning realizable mechanical properties. Both solid solution dispersion strengthening and crystal grain refining are known methods of mechanical properties of alloys enhancing. They are successfully applied to HSLA wrought steels elaboration by microalloying with interstitial carbide/nitide/carbonitride forming elements (Nb, V, Ti). Unfortunately, this method was not extended yet to sintered steels, probably due to difficulties to prevent oxidation of microalloying elements - with high affinity for oxygen, and also to assure their good homogenization with the iron base powder at the required small proportions. Only few information are published on this matter. This paper presents a synthesis of results obtained by authors concerning possibilities of Nb, V and Ti carbides/nitrides formation in the Fe matrix at sintering, of their oxidation prevention and good homogenization to overcome the above mentioned difficulties, appropriate technological routes being proposed.