The effect of heat treatment on toughness and wear resistance of Fe-Cr-C-Nb alloys

Abstract

Alloying with niobium improves the mechanical properties of the high chromium irons. The alloy containing appriximately 3 %Nb gives the best compromise between wear resistance and toughness. These properties were improved as a result of the positive influence of niobium on the microstructure, especially in the formation of nodular-shaped niobium carbides and the morphological changes of eutectic M7C3 carbides due to the presence of niobium. The fracture toughness of the high-temperature heat treated tested alloys was lower than that of the as-cast alloys because the matrix containing a considerable amount of martensite did not effectively prevent the crack propagation.

Legiranje niobijumom poboljšava mehanička svojstva visokohromnih gvožđa u livenom stanju. Legura koja sadrži približno 3% Nb ima dobru kombinaciju otpornosti na habanje i žilavosti. Ove osobine su poboljšane kao rezultat pozitivnog uticaja niobijuma na mikrostrukturu, posebno na formiranje nodularnog oblika niobijum karbida i morfoliških promena eutektičkog M7C3 karbida usled prisustva niobijuma. Žilavost ispitivanih legura nakon visokotemperaturnog termičkog tretmana je manja negu u livenom stanju, zato što metalna osnova koja sadrži značajnu količinu martenzita nije dovoljno efikasna u sprečavanju širenja prsline.