We recommend microalloyed steels containing Ti, Nb, and V, as well as inherently fine-grained steels. These materials effectively suppress abnormal grain growth at high temperatures by pinning grain boundaries through precipitated phases, making them suitable for long-term high-temperature service environments in hot runner systems.
1. Ti-containing steel (titanium carbide reinforced type)
Representative grades: H13+Ti, 4Cr5MoSiV1-Ti
Suppression mechanism: Ti forms highly stable TiC (titanium carbide), which is not easily dissolved at high temperatures, pinning grain boundaries for a long time, providing the strongest resistance to grain growth.
Applicable scenarios: High-temperature core areas such as nozzles and manifolds, especially suitable for long-term continuous production.
Advantages: TiC hardly dissolves below 1200°C, providing a durable grain boundary pinning effect.
2. Niobium Carbide-Reinforced Steel
Representative Grades: H13+Nb, 3Cr2W8V-Nb
Suppression Mechanism: NbC precipitates during austenitization, effectively preventing grain engulfment, particularly suitable for conditions with large temperature fluctuations.
Applicable Scenarios: Hot runner areas with frequent temperature changes, or molds requiring multiple heat treatments for repair.
Features: NbC has moderate solubility and can dynamically precipitate during recrystallization, achieving "self-healing" pinning.
3. Vanadium Carbide-Reinforced Steel
Representative Grades: H13+V, 5CrNiMo-V
Suppression Mechanism: VC particles exist stably in the medium-high temperature range (600–900°C), providing good pinning force.
Applicable Scenarios: Medium temperature range or auxiliary runner components; relatively low cost.
Note: VC is easily soluble at ultra-high temperatures; not recommended for extreme environments exceeding 1000°C.
4. Inherently Fine-Grained Steel (Al-Deoxidized Type)
Representative Grades: Al-Killed H13, Fine-Grained H13
Inhibition Mechanism: Al deoxidation forms a dispersed AlN distribution, preventing grain coarsening during heating.
Application Scenarios: Preferred for new mold manufacturing, ensuring a fine and uniform original microstructure (grain size 5-8).
Protection Principle: AlN functions from the initial heating stage, preventing excessive austenite grain growth.
