HPDC molds material directly affects mold life, production efficiency, and part quality.
The core material of HPDC molds is alloy tool steel, which achieves high heat resistance, wear resistance, and fatigue resistance through precision machining and surface treatment.
The core requirements of the HPDC molds material
In the HPDC process, the mold is subjected to high pressures (10–175 MPa), high temperatures (up to 600–1000°C for molten metal), and repeated thermal shocks.
High thermal strength: resists high temperature softening
Thermal fatigue resistance: Reduces cracks caused by repeated heating and cooling
Abrasion resistance: Resists the erosion of metal flow
Corrosion resistance: Resists chemical attack by molten metal
High thermal conductivity: accelerates cooling to shorten production cycle time
Dimensional stability: ensures part accuracy
Commonly used HPDC molds material types
Hot Work Tool Steel H13 Steel
The most widely used die steel containing 5% chromium, 1% molybdenum and 1% vanadium, with excellent thermal fatigue resistance and wear resistance.
The electroslag remelting (ESR) process can improve the homogeneity of the material and reduce internal defects, which is suitable for aluminum and magnesium alloy die casting.
H11 steel
Similar to H13, but with lower carbon content and better toughness, it is suitable for scenarios with higher impact requirements.
Dievar Steel
Improved hot work steel with improved thermal crack resistance through the addition of tungsten and optimized molybdenum/vanadium ratio, resulting in a 20–30% increase in die life compared to H13.
Other alloy steels
DIN 1.2344 (European standard)
Similar to H13, used for high-precision molds, especially for complex structural parts.
SKD61 (Japanese Standard)
High molybdenum content enhances high temperature hardness, suitable for die casting of high melting point materials such as copper alloy.
Mold manufacturing and processing technology
Forging & Heat Treatment
Staged quenching (e.g. 425°C sectional quenching) can improve impact toughness (up to 26J) and avoid brittleness caused by bainite structure.
Surface treatment
Enhancing wear resistance by nitriding (increasing surface hardness to 1000–1200 HV) or PVD coatings (e.g., CrN, TiAlN) extends mold life by 30–50%.
Cooling system design
Optimize the layout of the internal waterway of the mold, combined with external spray cooling, control the thermal gradient and reduce thermal stress.
Key Performance Requirements for Material Selection
Thermal fatigue resistance
HPDC molds are subjected to repeated quenching and quenching (molten metal temperatures can reach temperatures above 700°C), resulting in the accumulation of thermal stresses.
Although H13 ESR steel has deep cracks in the thermal cycling test, it can significantly improve the impact toughness to 26J through staged quenching
Such as 425°C sectional quenching, which is better than the traditional process.
High Temperature Strength and Ductility
Materials need to maintain high hardness and creep resistance at high temperatures.
Due to the optimised alloy composition, Dievar steel retains its high hardness (approx. 45 HRC) at 600°C, making it suitable for long-term high-temperature work.
Resistance to molten metal erosion
Aluminum and magnesium alloys are easy to react with the surface of the mold under high pressure.
H13 steel is formed by adding vanadium and molybdenum elements to form carbides, which effectively slows down the erosion rate.
Ease of processing and maintenance
The mold material needs to have good machinability to adapt to the precision machining of complex cavities.
For example, the ESR process improves the purity of H13 steel and reduces processing defects.
Future Development Trends
New mold materials
Development of steel grades containing rare earth elements (e.g. H13 Ce) to further improve creep resistance and high-temperature strength.
Ceramic matrix composites, such as SiC-reinforced steels, exhibit better erosion resistance in the laboratory.
Intelligent mold design
Combined with AI simulation, the mold temperature field distribution is optimized, the thermal stress concentration is reduced, and the mold life is prolonged.
