L6 Tool Steel | 1.2714 | 55NiCrMoV7 | SKT4 | BH224/5
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 shoul...
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.
1. Relevant Steel Specification of L6 Tool Steel
2. AISI L6 Steel Chemical Composition and Steel Equivalents
|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|
|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|
3. 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
|Poisson’s ratio||0.27- 0.30||0.27- 0.30|
|Elastic modulus||190-210 GPa||27557-30457 ksi|
4. 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).
5. AISI L6 Tool Steel Heat Treatment
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).
Quench L6 tool steel in oil to 66-51°C (150-125°F).
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).
minimize the possibility of cracking, the steel should be tempered
immediately after hardening and should be heated slowly to the desired
Annealing of steel L6 must be performed after hot working and before re-hardening.
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.
6. Machinability of Steel L6
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.
7. Applications of ASTM A681 L6 Tool Steel
L6 cold working tool steel is for general purpose tools and dies where
greater toughness is required, but with some sacrifice of
Typically used below applications:
blanking and forming dies,