Vanadium (V)
Vanadium is a transition metal primarily used as a micro-alloying element in high-strength low-alloy (HSLA) steels. Even tiny additions (0.02–0.15%) dramatically increase strength through grain refinement and precipitation hardening. Vanadium is also gaining importance in vanadium redox flow batteries for grid-scale energy storage.
Properties
- Density
- 6,000 kg/m³
- Melting Point
- 1,910 °C
- Boiling Point
- 3,407 °C
- Thermal Conductivity
- 30.7 W/(m·K)
- Electrical Resistivity
- 1.97 × 10⁻⁷ Ω·m
- Tensile Strength
- 500–700 MPa
- Yield Strength
- 350–500 MPa
- Hardness
- 60–70 HV
- Elongation
- 15–20%
- Crystal Structure
- BCC
Common Grades
- FeV (50–80% V): Ferrovanadium. Primary addition for HSLA steels, rebar, and structural sections.
- V₂O₅ (Vanadium pentoxide): Key compound for ferrovanadium production, catalysts, and vanadium batteries.
- V-N (Vanadium nitrogen): Vanadium nitride additive. Provides both V and N for optimal grain refinement in steel.
- V 99.5%: Pure vanadium metal. Aerospace titanium alloys (Ti-6Al-4V), superconductors.
Applications
- Steel Micro-Alloying: HSLA steels, reinforcement bars, pipeline steels, automotive sheet, structural sections
- Energy Storage: Vanadium redox flow batteries (VRFB) for grid storage, renewable energy integration
- Aerospace: Essential component of Ti-6Al-4V (the most-used titanium alloy)
- Chemical: Sulfuric acid production catalyst (V₂O₅), maleic anhydride production
FAQ
How does vanadium strengthen steel?
Vanadium strengthens steel through two mechanisms: (1) grain refinement — V(C,N) precipitates pin austenite grain boundaries during rolling, producing a finer ferrite grain size, and (2) precipitation hardening — fine V(C,N) particles precipitate during cooling, impeding dislocation movement. As little as 0.05% V can increase yield strength by 100+ MPa.
What are vanadium redox flow batteries?
VRFBs store energy in vanadium electrolyte solutions (V²⁺/V³⁺ and V⁴⁺/V⁵⁺) flowing through a cell stack. Advantages include 20+ year lifespan, unlimited cycling with no degradation, independent scaling of power (cell stack) and energy (tank volume), and 100% depth of discharge. Ideal for 4–12 hour grid storage.
How is vanadium different from niobium for steel micro-alloying?
Both refine grain size and form strengthening precipitates, but they work at different temperatures. Niobium precipitates (NbC) form at higher temperatures during rolling and are more effective at grain refinement. Vanadium precipitates (VN/VC) form at lower temperatures during cooling, providing precipitation hardening. Many HSLA steels use both elements together for optimum properties.