High Toughness, Heat Checking Resistance, Ymt8518 Mold Steel for Hot Work Casting

• Customization: Available
• Type: Alloy Steel Bar
• Standard: AISI, ASTM, DIN, JIS, GB
• Model NO.: YMT8518
• Application: Tool Steel Bar
• Transport Package: Container and / or Metal Framework
• Specification: in terms of mm x mm x mm
• Trademark: YMT
• Origin: China
• HS Code: 7224901000

Product Description

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.