Steel L6
AISI/SAE L6 · UNS T61206
L6 is a nickel–chromium–molybdenum low-alloy tool steel (UNS T61206) selected for toughness and shock resistance rather than maximum wear life.
Reference datasheet — L6 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the A condition
L6 tempers and conditions
L6 is supplied in 6 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Standard stocked supply condition for machining and forming before hardening. | 420 | 730 | 22 | 197 HB | — |
Pre-hardened | Large die blocks and mould bases supplied ready to machine with no further heat treatment. | 950 | 1,120 | 14 | 36 HRC | — |
Oil quenched from 845–870 °C, tempered ~510–540 °C | Maximum-toughness setting for heavy shock tooling, forging die inserts and large punches. | 1,250 | 1,420 | 10 | 44 HRC | — |
Oil quenched, tempered ~400–450 °C | Balanced hardness/toughness for shear blades, chisels and impact punches. | 1,500 | 1,750 | 6 | 52 HRC | — |
Oil quenched from 845–870 °C, tempered ~250–320 °C | Standard hardened working condition for dies, punches, blades and knife blanks. | 1,700 | 2,000 | 3.5 | 56 HRC | — |
Oil quenched, low temper ~175–205 °C | Maximum hardness/wear setting for cutting edges and blades where impact is moderate. | 1,900 | 2,250 | 1.5 | 60 HRC | — |
What is L6?
L6 is a nickel–chromium–molybdenum low-alloy tool steel (UNS T61206) selected for toughness and shock resistance rather than maximum wear life. It is supplied annealed at 197 HB (730 MPa tensile, 420 MPa yield, 22 % elongation), pre-hardened at 34–38 HRC, or oil hardened and tempered from 42–46 HRC up to 58–62 HRC, and is common in large impact-loaded tooling. Its 0.7 % carbon limits weldability (score 20), service temperature is capped near 400 °C and corrosion resistance is minimal (score 11). S7 is the usual alternative when still higher shock resistance is needed. L6 has a density of 7.87 g/cm³ (0.284 lb/in³), heavier than 92% of steel grades. It melts at 1,420°C (2,588 °F). L6 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 730 MPa (106 ksi) — weaker than 53% of steel grades. Elongation at break is 22% and the elastic modulus is 207 GPa (30 Msi).
What is L6 used for?
- shear blades
- punches
- large forming dies
- machine knives
- arbors
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to weld — 20/100, worse than 84% of steel grades
L6 properties
Typical room-temperature values for L6-A; bars are the position among steel grades.
Physical3
L6 has a density of 7.87 g/cm³ (0.284 lb/in³), heavier than 92% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
L6 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 730 MPa (106 ksi) — weaker than 53% of steel grades. Elongation at break is 22% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
L6 is rated for continuous service to 400°C (752 °F). It conducts heat at 38 W/m·K (22 BTU/hr·ft·°F), worse than 69% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
L6 conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of L6 takes about 33 MJ of energy and emits 2.4 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 30%.
Manufacturability8
L6's machinability is good (55/100, better than 62% of steel grades); weldability poor (20/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. L6 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with L6
Is L6 easy to machine?
Machine in the annealed condition (≈60 % of 1212) with sharp carbide or cobalt HSS tools; after hardening above ~50 HRC only grinding, EDM or hard turning with CBN is practical.
Can L6 be welded?
Poor weldability due to 0.7 % C — preheat 300–350 °C, use matching or low-hydrogen filler, weld hot and temper immediately to avoid quench cracks; repair welding only.
Can L6 be formed, bent or molded?
Hot work 1050–870 °C then slow cool and spheroidize anneal at 760–790 °C; cold forming is limited to light bending in the annealed state. Harden from 845–870 °C, oil quench, temper immediately at 175–540 °C for the target hardness.
L6 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| CASTM A681 | 0.65 – 0.75 | 0.7 |
| Mn | 0.25 – 0.8 | 0.55 |
| Si | 0.1 – 0.5 | 0.3 |
| Cr | 0.6 – 1.2 | 0.85 |
| Nitoughness/hardenability | 1.25 – 2 | 1.6 |
| Mooptional addition | ≤ 0.5 | 0.3 |
| Voptional, grain refinement | ≤ 0.2 | 0.1 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on L6?
Not corrosion resistant — protect with oil, black oxide, phosphate, nitriding or hard chrome; polishes well when hardened, and vacuum/salt-bath hardening minimises scale and decarburisation.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel L6 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T61206
How much does L6 cost?
L6 is a premium-cost steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
L6 — frequently asked
What is L6 used for?
L6 is typically used for shear blades, punches, large forming dies, machine knives and arbors. In short: shock-resistant Ni-Cr-Mo tool steel; available pre-hardened 34–38 HRC; suited to large impact tools.
What is the yield strength of L6?
L6 has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 730 MPa (106 ksi) — weaker than 53% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is L6 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine in the annealed condition (≈60 % of 1212) with sharp carbide or cobalt HSS tools; after hardening above ~50 HRC only grinding, EDM or hard turning with CBN is practical.
Can L6 be welded?
Not readily — weldability is rated poor (20/100). Poor weldability due to 0.7 % C — preheat 300–350 °C, use matching or low-hydrogen filler, weld hot and temper immediately to avoid quench cracks; repair welding only.
What surface finishes work on L6?
Not corrosion resistant — protect with oil, black oxide, phosphate, nitriding or hard chrome; polishes well when hardened, and vacuum/salt-bath hardening minimises scale and decarburisation.
Can L6 be formed, bent or molded?
Hot work 1050–870 °C then slow cool and spheroidize anneal at 760–790 °C; cold forming is limited to light bending in the annealed state. Harden from 845–870 °C, oil quench, temper immediately at 175–540 °C for the target hardness.
What is the maximum service temperature of L6?
L6 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does L6 cost?
L6 is a premium-cost steel ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A681 — Standard Specification for Tool Steels Alloy — ASTM International (2022)
- ASM Handbook Vol. 1: Properties and Selection: Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- ASM Handbook Vol. 4: Heat Treating (Heat Treating of Tool Steels) — ASM International (1991)
- SAE J437 / J438 Tool and Die Steels — SAE International (2019)
- Low-alloy special-purpose tool steel (L6 type) product data — Tool steel producers (composite of published datasheets) (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.