Description
DH31-EX is a hot working die steel with the best balance of strength and toughness showing the comparable softening resistance to SKD7 and twice hardenability as that of SKD61.
Applications include:
Aluminum Die Cast Dies
Aluminum Die Cast Parts
Hot Forging Dies
Hot Pressing Dies
Aluminum Extrusion Dies
Unique Characteristics
- High hardenability
High toughness is obtained even in large size die. - High strength
High softening resistance at elevated temperature contributes to high wear resistance. - High toughness
DH31-EX has higher toughness than that of SKD61. - High heat check resistance
Excellent heat check resistance leads to longer life.
Product Brochure
CHEMICAL COMPOSITION
PHYSICAL PROPERTIES
Specific heat
Thermal conductivity
Density
Characteristics
- Quenching temp: 1030°C
- T.P. size: 10H x 10W x 15L
Softening resistance
- Holding temp.: 600°C
- Quenching temp: 1030°C x 30min. –> 150 Dia. Bar, AC
- T.P. size: 10H x 10W x 15L
Heat check resistance
Heat check resistance is further improved by increasing hardness without deteriorating toughness.
An example to improve heat check resistance (200mmm thickness air cool quenched die)
<Test procedures>
- Specimen: 15mm
- I/Heating: 20<-> 700C
- Number of cycles: 1000 times
Toughness
- Quenching temp: 1030°C x 30min. –> 150 Dia. Bar, AC
- T.P. size: L
Elevated temperature tensile properties
- T.P. size: Ø 8 x 40L
Erosion resistance
Creep properties
Hardenability
Bainite hardenability
As Bainite transformation starting time is twice as that of SKD61, 130min., quenching operations is easily and safely carried out without troubling such as toughness deterioration in large size dies.
Quenching cooling time vs. toughness
Cooling time of mid portion from 1030°C to 300°C (min)
TP size: Ø440
Quenching temp: 1030°C
Surface Hardening Properties
- Daido Amistar’s originally developed process.
- PW process improves wear, fatigue and corrosion resistance.
- PS process improves scuffing and erosion resistance.
Machinability
- DH31-EX shows good machinability as high strength-high tough grades.
 
- Recommended machining conditions
Repair Welding Conditions
- TIG manual welding condition
Recommended Reading
Specific heat
Thermal conductivity
Density
Characteristics
- Quenching temp: 1030°C
- T.P. size: 10H x 10W x 15L
Softening resistance
- Holding temp.: 600°C
- Quenching temp: 1030°C x 30min. –> 150 Dia. Bar, AC
- T.P. size: 10H x 10W x 15L
Heat check resistance
Heat check resistance is further improved by increasing hardness without deteriorating toughness.
An example to improve heat check resistance (200mmm thickness air cool quenched die)
<Test procedures>
- Specimen: 15mm
- I/Heating: 20<-> 700C
- Number of cycles: 1000 times
Toughness
- Quenching temp: 1030°C x 30min. –> 150 Dia. Bar, AC
- T.P. size: L
Elevated temperature tensile properties
- T.P. size: Ø 8 x 40L
Erosion resistance
Creep properties
Hardenability
Bainite hardenability
As Bainite transformation starting time is twice as that of SKD61, 130min., quenching operations is easily and safely carried out without troubling such as toughness deterioration in large size dies.
Quenching cooling time vs. toughness
Cooling time of mid portion from 1030°C to 300°C (min)
TP size: Ø440
Quenching temp: 1030°C
Surface Hardening Properties
- Daido Amistar’s originally developed process.
- PW process improves wear, fatigue and corrosion resistance.
- PS process improves scuffing and erosion resistance.
- DH31-EX shows good machinability as high strength-high tough grades.
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- Recommended machining conditions
- TIG manual welding condition