Meaning
The proportion of vanadium carbide precipitates in a tool steel alloy determines the wear resistance of the tooling components. In the moulding of highly filled or abrasive plastics, the vanadium carbide fraction affects the rate of adhesive and abrasive wear on screw flights, barrels, and gates. This microstructural phase consists of hard particles distributed throughout the steel matrix to resist scratching.
It is bounded by the fracture toughness of the alloy.
Material Properties
High-alloy steels rely on specific carbide distributions to achieve high hardness without becoming overly brittle. A higher vanadium carbide fraction provides superior protection against the abrasive action of glass-filled polymer melts. This phase exhibits a hardness that exceeds that of standard chromium carbides, making it highly effective at resisting wear from mineral and glass fillers.
This composition prevents premature dimensional changes in critical tool inserts.
Tooling Performance
Long-term stability in high-wear zones of the mould depends on the durability of the alloy microstructure. When a tool steel with a low vanadium carbide fraction is used, the gate area suffers rapid erosion. This wear leads to flash and dimensional instability in the moulded parts.
Processing Effect
Machining and polishing tool steels with high carbide contents require specialized grinding techniques and tooling. Because the vanadium carbide fraction is extremely hard, it resists standard cutting tools and can complicate the manufacturing of intricate mould cavities. Mould makers use electric discharge machining to shape these materials without causing surface micro-cracks.
Proper stress relieving after machining prevents premature tool failure in production, ensuring that the hard carbide phase remains securely anchored within the steel matrix and does not spall under cyclic high-pressure injection forces.
