Influence of Vanadium Microalloying on Deformation-Induced Pearlite Transformation of Eutectoid Steel

Abstract

In order to investigate the influence of vanadium microalloying on deformation-induced pearlite transformation (DIPT) of eutectoid steel, thermomechanical simulation tests were carried out in this study. The following four compositions of vanadium microalloying were applied in the tests: vanadium free in Steel A, vanadium content of 0.1 mass% in Steel B, vanadium content of 0.27 mass% in Steel C, and vanadium content of 0.1 mass% with the addition of 0.02 mass% N in Steel D. The dissolution of vanadium and precipitation of vanadium carbides, nitrides, or carbonitridesand the effect of vanadium microalloying on the fraction and morphology of deformation-induced pearlite for different magnitudes of strain were examined, and the mechanism of the effect was elucidated. The results revealed that DIPT could be significantly improved by vanadium microalloying with the addition of N but decreased and postponed without the addition of N because vanadium nitrides or carbonitrides were precipitated in austenite under a small strain and facilitated the nucleation of pearlite both along the boundary of austenite grain (AG pearlite) and intragranular (IG pearlite). Moreover, transformation kinetics of DIPT was fitted and compared. The results further revealed that the rate of DIPT in vanadium-microalloyed steel with the addition of N was twice as fast as that in the vanadium-free steel. In order to ensure the complete spheroidization of lamellar cementites in vanadium-microalloyed steel, a comparison of the morphology of cementites revealed that a greater magnitude of strain was required.

Effect of heat treatment process on precipitation of V microalloyed steel

“…Through further analysis, it is known that the transformation from pearlite to austenite primarily occurs in this temperature range [37][38][39]. With a further increase in temperature, there was a very small endothermic peak near 1115°C corresponding to the dissolution of V. The relatively small peak in heat flow at this endothermic peak was because the V content in the test steel was relatively low, so less heat was absorbed when V fully dissolved [40]. During the cooling process, there was a convex, exothermic peak near 733°C.…”

Reduction and Nitridation of Iron/Vanadium Oxides by Ammonia Gas: Mechanism and Preparation of FeV45N Alloy

“…Metals 2020, 10, 356; doi:10.3390/met10030356 www.mdpi.com/journal/metals Metals 2020, 10, 356 2 of 12 (>2673 K). Compared with vanadium nitride, ferrovanadium nitride has better affinity and higher density (>5 g/cm 3 ), which makes it more easily absorbed by molten steel and can increase the recovery of vanadium and nitrogen, thereby reducing the production cost and improving the mechanical properties of the steel [10,11]. Traditionally, ferrovanadium nitride could be synthesized by direct nitridation of ferrovanadium alloy, carbothermal reduction-nitridation or hydrogen-based reduction-nitridation of corresponding metallic oxides, using nitrogen or ammonia gas as nitrogen sources.…”

Microstructure Characterization and Strengthening Mechanism Analysis of X100 Pipeline Steel

“…Strengthening mechanisms [3][4][5][6]. At present, the microstructure of pipeline steel with X52 strength grade and below is mainly "polygonal ferrite + pearlite", with a carbon content of <0.12 wt.% and manganese content of <1.4 wt.%.…”