In ASTM A681 standard, L6 steel grade is in L-type for special purpose tool steels. AISI L6 tool steel is in the general class of alloy, oil-hardening tool steel that is characterized by good toughness. ASTM L6 tool steel is suitable for use as tools, dies, and machine parts, which require a good combination of hardness and toughness.
Due to its lower carbon content and relatively high nickel content, L6 tool steel has slightly better shock-resistance than more highly alloyed types and should be used where some wear-resistance can be sacrificed for increased toughness.
Otai steel is able to supply AISI L6 tool steels materials with different shape and size range, according to different requirements.
1. Supply Range of ASTM L6 Tool Steel
L6 Steel Round Bar: diameter 8mm – 800mm
L6 Steel Plate: thickness 2mm –300mm x width 200mm – 800mm
Other sizes of L6 steel or as per customer’s requirements
Surface Finish: Black, Rough Machined,Turned or as per given requirements.
2. Relevant Steel Specification of L6 Tool Steel
| Country | USA | German | Japan | British |
| Standard | ASTM A681 | DIN EN ISO 4957 | JIS G4404 | BS 4659 |
| Grades | L6/T61206 | 1.2714/55NiCrMoV7 | SKT4 | BH224/5 |
3. AISI L6 Steel Chemical Composition and Steel Equivalents
| ASTM A681 | C | Mn | P | S | Si | Cr | V | Mo | Ni | |||||||
| L6/T61206 | 0.65 | 0.75 | 0.25 | 0.80 | 0.03 | 0.03 | 0.10 | 0.50 | 0.60 | 1.20 | . . . | . . . | . . . | 0.50 | 1.25 | 2.00 |
| DIN ISO 4957 | C | Mn | P | S | Si | Cr | V | Mo | Ni | |||||||
| 1.2714/55NiCrMoV7 | 0.50 | 0.60 | 0.60 | 0.90 | 0.03 | 0.02 | 0.10 | 0.40 | 0.80 | 1.20 | 0.05 | 0.15 | 0.35 | 0.55 | 1.50 | 1.80 |
| JIS G4404 | C | Mn | P | S | Si | Cr | V | Mo | Ni | |||||||
| SKT4 | 0.50 | 0.60 | 0.60 | 0.90 | 0.03 | 0.02 | 0.10 | 0.40 | 0.80 | 1.20 | 0.05 | 0.15 | 0.35 | 0.55 | 1.50 | 1.80 |
| BS 4659 | C | Mn | P | S | Si | Cr | V | Mo | Ni | |||||||
| BH224/5 | 0.49 | 0.57 | 0.70 | 1.00 | 0.03 | 0.025 | . . . | 0.35 | 0.70 | 1.10 | . . . | . . . | 0.25 | 0.40 | 1.25 | 1.80 |
4. ASTM L6 Tool Steel Mechanical Properties
Steel L6 Physical Properties
- Modulus of elasticity [103 x N/mm2]: 215
- Density [g/cm3]: 7.84
- Thermal conductivity [W/m.K]: 36.0
- Electric resistivity [Ohm mm2/m]: 0.30
- Specific heat capacity[J/g.K]: 0.46
Mechanical Properties of L6 Steels
| Properties | Metric | Imperial |
| Poisson’s ratio | 0.27- 0.30 | 0.27- 0.30 |
| Elastic modulus | 190-210 GPa | 27557-30457 ksi |
5. Forging of L6 Tool Steel
Forge at 1079°C (1975 F) down to 871°C (1600 F). Do not forge below 843°C (1550 F).
6. AISI L6 Tool Steel Heat Treatment
Hardening
Preheating: Heat steel L6 at a rate not exceeding 204°C (400°F) per hour (222°C per hour) to 621-677°C (1150-1250°F) and equalize. Soak for 30 minutes for the first inch (25.4 mm) of thickness, plus 15 minutes for each additional inch (25.4 mm).
Quenching
Quench L6 tool steel in oil to 66-51°C (150-125°F).
Tempering
Temper L6 steels immediately after quenching. Hold at temperature for 1 hour per inch (25.4 mm) of thickness when tempering at 204°C (400°F), 4 hours minimum, then air cool to ambient temperature.
However, where increased toughness is desired, at a sacrifice of some hardness, higher tempering temperatures are often used.
AISI L6 steel does not become brittle, as many other die steels do, when tempered in the range of 232°C to 426°C (450 to 800°F).
To minimize the possibility of cracking, the steel should be tempered immediately after hardening and should be heated slowly to the desired tempering temperature.
Annealing
Annealing of steel L6 must be performed after hot working and before re-hardening.
Heat to 760°C (1400°F) and hold one hour per inch of maximum thickness. Then cool slowly with the furnace at a rate not exceeding 28°C per hour(50°F per hour) to 538°C (1000°F). Continue cooling to ambient temperature in the furnace or in air.
For improved machinability, hold at 760°C (1400°F) for 1 hour per inch (25.4mm) of maximum thickness; 2 hours minimum. Then cool slowly with the furnace cool from 677°C (1250°F) to 760°C (1400°F), hold for 8 hours, then air cool to ambient temperature.
Because of its air-hardening ability, steel L6 should not be normalized.
7. Machinability of Steel L6
Machinability of tool steel L6 is very good. It rates 90% of the machinability of the W-group water hardening low alloy steels rated 100% as a baseline.
8. Applications of ASTM A681 L6 Tool Steel
AISI L6 cold working tool steel is for general purpose tools and dies where greater toughness is required, but with some sacrifice of abrasion-resistance.
Typically used below applications:
- spindles,
- forming rolls,
- punches,
- blanking and forming dies,
- trimmer dies,
- clutch parts,
- pawls,
- bearings,
- chucks parts,
- rollers,
- knuckle pins,
- clutch pins,
- shear blades
Yunge steel could supply AISI L6 tool steel with good quality and best price for your different application requirements. Modified L6 steel chemical composition is available with detailed elements requirements. Customized dimension of L6 steel is available against given size information and details.