Precipitation Characteristics and Mechanism of Vanadium Carbides in a V-Microalloyed Medium-Carbon Steel

Abstract

The precipitation characteristics and mechanism of vanadium carbides during isothermal transformation at 650°C in a V-microalloyed medium-carbon steel were investigated through scanning electron microscopy and transmission electron microscopy as well as dilatometry test. Five morphologies of vanadium carbides were found to precipitate at different nucleation sites during the transformation. Two kinds of interphase precipitation form simultaneously in both pro-eutectoid and pearlitic ferrites. The linear arrays of fine interphase precipitates are parallel to the c/a interface, and the fine needles of interphase precipitates are perpendicular to the c/a interface. The vanadium carbides of long or short fibers, coarse particles and fine particles form in both pro-eutectoid and pearlitic ferrites, displaying different precipitation distributions and orientation relationships with ferrite. The precipitation mechanisms of vanadium carbide precipitates with different modes were proposed, and the precipitation sequence of various vanadium carbide precipitates was finally ascertained.

The Effect of the Dilution Level on Microstructure and Wear Resistance of Fe-Cr-CV Hardfacing Coatings Deposited by PTA-P

“…From the images obtained by scanning electron microscopy and using Particle Separation methodologies of the Fiji free available software [40,52], the percentual volume Six transmission electron microscopy (TEM) classifications of VC [49] morphologies have been reported in the literature: (i) undissolved carbides, (ii) austenite precipitation, (iii) interphase precipitation, (iv) "fibrous" morphology, (v) matrix precipitation, and (vi) precipitation on dislocations. However, these differences between the precipitates and the precipitation sequence of the various morphologies were studied for levels below 1% of V [49,50]. Although the morphologies presented in these studies are for very low levels of V, compared to the content of this study, it is known that when the content of V is greater than the percentage of C, most of the C will combine with the V until saturation [51].…”