Effect of vanadium addition on the microstructure and mechanical properties of low carbon micro-alloyed powder metallurgy steels

Abstract

In the present experimental work, the effects of vanadium additions on the microstructures and mechanical properties of powder metallurgy (PM) steel and microalloyed powder metallurgy (PM) steels were investigated. The microstructures of the PM steel and microalloyed PM steels were characterized by optic microscope, SEM and EDS. Experimental results showed that vanadium microalloyed steels can be produced by PM technology. The addition of vanadium limits grain growth during austenitization prior to air cooling and increases the strength in the sintered conditions. By limiting austenite grain growth, the precipitates result in significant improvement in strength.

The Effect of the Sintering Temperature and Addition of Niobium and Vanadium on the Microstructure and Mechanical Properties of Microalloyed PM Steels

“…High strength and good toughness in microalloyed steels are achieved by a combination of microalloying and controlled rolling [21]. During sintering and slow cooling from sintering temperature, NbC(N) or VC(N) precipitates form in austenite and in ferrite during the austenite-ferrite transformation, or after transformation as suggested by Erden et al [3]. This leads to an increase in strength compared to the niobium and vanadium-free alloy.…”

“…Due et al [22] have observed an increase in the wear resistance and hardness of low carbon steel by TiC-VC precipitates. Some other studies [1][2][3]23] indicated that carbides and nitrides formed in microalloyed steels improve the hardness and strength. These studies argued that it was the solid solution hardening that contributed to strength less than carbide and nitride precipitation.…”

“…Although vanadium is highly soluble in austenite, it is less soluble in ferrite. Contrary to the other microalloys, vanadium is known to increase the ferrite formation rather than prevent it [3]. VN precipitates prevent grain coarsening and consequently ferrite grain structures are formed which increases the toughness and strength.…”

“…The type, size and distribution of the compounds of microalloying elements with carbon and nitrogen are important for precipitation hardening. Vanadium is the most important element due to its high solubility in austenite [3]. The major function of vanadium, as a microalloying element, is precipitation hardening.…”

“…VN can form in austenitic structures of high carbon steels (0.4%), especially when the amount of nitrogen is high, and refine the grain size similar to NbC. Since vanadium forms precipitates, it increases the strength of the steel [2][3][4][5]. Although vanadium is highly soluble in austenite, it is less soluble in ferrite.…”