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YMT 8518R is a groundbreaking high alloyed Chromium-Molybdenum-Vanadium Hot Work Tool steel. Expertly engineered for the most rigorous high-pressure Light Alloys (Al-Mg) die casting dies, it complies with NADCA #207 standards, ensuring superior annealed microstructure, minimal banding segregation, and exceptional impact capability. YMT8518R is designed to achieve unparalleled performance levels. It is delivered in annealed condition with a hardness value below 230 HB.
Main features
excellent isotropy;
• high mechanical properties and strength
• high hardenability
• high thermal conductivity
• high tempering resistance;
• high thermal stability
• high thermal fatigue and hot cracking resistance;
• excellent fracture toughness in hot and cold conditions;
• high ductility
• high wear and erosion resistance
• high oxidation resistance
• required very high core temperature to optimally perform
• suitable for medium and large dies (up to 2 tons)
• suited for long run dies producing thick walled pieces
Main application
• High pressure Aluminum/Magnesium die casting molds;
• Molds for low pressure Aluminum die castings;
• Molds for Aluminum gravity die castings;
Chemical analysis
| Alloy | C | Si | Mn | Cr | Mo | V |
| % in weight | 0.32-0.40 | 0.10-0.30 | 0.30-0.50 | 4.80-5.50 | 2.00-2.40 | 0.40-0.70 |
Physical and mechanical properties
Main physical properties
| 200 °C | 400°C | 600°C | |
| Modulus of elasticity [MPa] | 210 | 180 | 145 |
| Coefficient of thermal expansion [10-6/K] | - | 12.8 | 13.4 |
| Thermal conductivity [W/m K] | - | 31.0 | 33.0 |
Main mechanical properties
| 400°C | 500°C | 600°C | |
| Ultimate Tensile Strength (UTS) [MPa] | 1200 | 1100 | 850 |
| Yield stress (YS) [MPa] | 1000 | 910 | 610 |
| Soft annealing | |||
| Suggested temperature | 850°C | ||
| Heating | Max 50°C/h | ||
| Soaking time | Minimum 120 min from the temperature settlement | ||
| Cooling | Slow in the furnace at max 25°C/h to 600°C afterward at room temperature | ||
| Stress Relieving | |||
| Suggested temperature | For material in annealed condition: 650 °C. For material in QT condition or after machining: 50°C less than the last tempering | ||
| Heating | Max 100 °C/h | ||
| Soaking time | Minimum 120 min from the temperature's settlement | ||
| Cooling | Slow in the furnace at max 25 °C/h to 200°C, afterward at room temperature | ||
| Hardening | |||
| First pre-heating temperature | 400 °C | ||
| Heating | Max 150 °C/h | ||
| Soaking time | 25 min every 25 mm thickness | ||
| Second pre-heating temperature | 600 °C | ||
| Heating | Max 150 °C/h | ||
| Soaking time | 20 min every 25 mm thickness or when (Ts-Tc) < 90 °C | ||
| Third pre-heating temperature | 800 °C | ||
| Heating | Max 150 °C/h | ||
| Soaking time | 20 min every 25 mm thickness or when (Ts-Tc) < 90 °C | ||
| Austenitizing temperature | 980°C | ||
| Heating | > 150°C/h | ||
| Soaking time | t = ( x + 39 ) / 2 or 30 min from (Ts-Tc) < 15 °C | ||
| Cooling | Air, vacuum cooling, salt bath, polymer in water | ||
| First tempering temperature | 550 °C | ||
| Soaking time | t' = 0,8 x + 120 | ||
| Cooling | Room temperature | ||
| Second tempering temperature | Based on mechanical properties required | ||
| Soaking time | t" = 0,8 x + 120 | ||
| Cooling | Room temperature | ||
| Third tempering temperature | 30-50 °C lower than the max temperature previously used | ||
| Soaking time | t'" = 0,8 x + 180 | ||
| Cooling | Slow cooling in the furnace up to 250 °C, afterward at room temperature | ||
Chrome plating
It can be Chrome plated in order to enhance the mechanical characteristics on the surface.
In order to prevent Hydrogen embitterment, within 4 hours of Chrome plating it is advisable to carry out heat treatment at 200 °C for about 4 hours.
Nitriding
It is suitable for ionic and gas nitriding. This treatment is very useful for molds subjected to
extremely stressful applications. The increase of the surface hardness, following nitriding, extends the component life cycle.
Polishing and photo engraving
It is the suitable material when polishing and photoengraving are needed. Thanks to its integrated manufacturing process, those material manufactured by our steel mill characterized by a high degree of purity.
