Low C-Cu-Ni-Mo Alloy Structural Sintered Steels with Small Titanium Additions

摘要

Titanium is a strong carbideitride-forming element, much stronger than Mo and Ni. Like Mo, it forms interstitial carbidesitrides/carbonitrides, but does not form complex carbidesitrides with Fe. These interstitial compounds may act as disperse phases, of a strengthening effect, in sintered steels. Starting from these considerations, this paper presents the results of investigations performed in order to establish the possibilities of mechanical properties of the common low C-Cu-Ni-Mo alloy structural sintered steels enhancing by small titanium additions. On thermodynamic bases, there were demonstrated the possibilities of the above mentioned compounds preferential formation in these steels during sintering in dissociated ammonia at both common and elevated temperatures, of their solving in austenite / ferrite and subsequent precipitation at cooling or artificial ageing. Experimental results obtained for 0.2 / 1.0 % fine Ti powder and 0.3 % graphite additions to Distaloy AB powder cold compacted and sintered in dissociated ammonia proved these predictions.