Steel L7
AISI/SAE L7 · UNS T61207
L7 (UNS T61207) is a chromium–vanadium low-alloy oil-hardening tool steel of the AISI L group, with higher hardenability than L2 where greater core strength and toughness are required.
Reference datasheet — L7 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 ANN condition
L7 tempers and conditions
L7 is supplied in 9 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose when maximum machinability or cold upsetting/heading of the 1 %C alloy is needed. | 390 | 700 | 28 | 183 HB | 8.2 % IACS |
ANNDefault Annealed | Standard stock condition for machining and forming before hardening. | 415 | 750 | 25 | 195 HB | — |
Hot rolled | Mill condition of large bar before annealing; only for rough stock and forging feed. | 520 | 950 | 15 | 25 HRC | 8 % IACS |
Normalized | Intermediate grain-refining step before spheroidizing or hardening of forged sections. | 560 | 1,000 | 12 | 30 HRC | 7.8 % IACS |
Cold drawn, annealed | Use for close-tolerance shafting and gauge blanks that will be hardened after light machining. | 620 | 830 | 12 | 217 HB | 8 % IACS |
Oil quenched and tempered to 50–52 HRC | Toughest hardened condition — shock-loaded shafts, arbors and heavy-section tooling. | 1,550 | 1,750 | 6 | 51 HRC | — |
Oil quenched and tempered to 54–56 HRC | Balance of wear and toughness for rolls, cams, collets and forming tools. | 1,750 | 1,950 | 4 | 55 HRC | — |
Oil quenched (≈830–845 °C) and tempered to 57–59 HRC | Standard working hardness for gauges, spindles, taps, bearing-type wear surfaces. | 1,950 | 2,150 | 2 | 58 HRC | — |
Oil quenched and stress-relief tempered to 60–62 HRC | Maximum hardness/wear for gauge blocks and light-duty cutting or burnishing tools; lowest toughness. | 2,050 | 2,300 | 1 | 61 HRC | — |
What is L7?
L7 (UNS T61207) is a chromium–vanadium low-alloy oil-hardening tool steel of the AISI L group, with higher hardenability than L2 where greater core strength and toughness are required. It is supplied hot-rolled, annealed, spheroidized or cold-drawn-annealed at about 415 MPa yield, 750 MPa tensile, 25 % elongation and 195 HB (92 HRB), and is quench-tempered in four bands from 50–52 to 60–62 HRC. Weldability is poor, corrosion resistance is nil, machinability is modest (48) and service is limited to roughly 250 °C; choose O1 or CrWMn when quench distortion must be minimised. L7 has a density of 7.84 g/cm³ (0.283 lb/in³), lighter than 78% of steel grades. It melts at 1,420°C (2,588 °F). L7 has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 56% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi).
What is L7 used for?
- clutch plates
- wrenches
- gripping jaws
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Difficult to weld — 15/100, worse than 91% of steel grades
- Limited service temperature — 250°C (482 °F), worse than 85% of steel grades
- Poor heat conductor — 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades
L7 properties
Typical room-temperature values for L7-ANN; bars are the position among steel grades.
Physical3
L7 has a density of 7.84 g/cm³ (0.283 lb/in³), lighter than 78% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical15
L7 has a yield strength of 415 MPa (60.2 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 56% of steel grades. Elongation at break is 25% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
L7 is rated for continuous service to 250°C (482 °F). It conducts heat at 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
L7 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of L7 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
L7's machinability is fair (48/100, worse than 57% of steel grades); weldability poor (15/100); formability poor (25/100).
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. L7 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with L7
Is L7 easy to machine?
Machine only in the annealed/spheroidized state with rigid setups and carbide or cobalt HSS; above ~50 HRC use grinding, hard turning with CBN, or EDM.
Can L7 be welded?
Poor weldability — 1 %C martensite cracks easily; if repair is unavoidable, preheat 300–350 °C, use matching or low-hydrogen filler, and temper immediately after welding.
Can L7 be formed, bent or molded?
Hot work 1050–870 °C then slow cool/anneal; cold forming limited to light bending or upsetting of spheroidized bar; harden by oil quench from 830–845 °C after preheat, temper immediately at 150–370 °C.
L7 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 |
|---|---|---|
| Chigh carbon for 60+ HRC potential | 0.95 – 1.05 | 1 |
| Mn | 0.25 – 0.8 | 0.45 |
| Si | 0.1 – 0.5 | 0.3 |
| Crmain hardenability/carbide former | 1.4 – 1.6 | 1.5 |
| Modistinguishes L7 from L3/52100; raises hardenability and core strength | 0.25 – 0.4 | 0.35 |
| Vresidual/optional grain refiner in some listings | ≤ 0.2 | 0.05 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on L7?
Takes a fine polish and hard chrome/nitride coatings well; supply and store oiled or black-oxided since the alloy has no corrosion resistance.
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 L7 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T61207
How much does L7 cost?
L7 is a standard-cost steel ($$), cheaper than about 71% 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.
L7 — frequently asked
What is L7 used for?
L7 is typically used for clutch plates, wrenches and gripping jaws. In short: higher hardenability than L2; tough Cr-V oil-hardening grade; 25 % elongation annealed.
What is the yield strength of L7?
L7 has a typical yield strength of 415 MPa (60.2 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 56% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is L7 easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Machine only in the annealed/spheroidized state with rigid setups and carbide or cobalt HSS; above ~50 HRC use grinding, hard turning with CBN, or EDM.
Can L7 be welded?
Not readily — weldability is rated poor (15/100). Poor weldability — 1 %C martensite cracks easily; if repair is unavoidable, preheat 300–350 °C, use matching or low-hydrogen filler, and temper immediately after welding.
What surface finishes work on L7?
Takes a fine polish and hard chrome/nitride coatings well; supply and store oiled or black-oxided since the alloy has no corrosion resistance.
Can L7 be formed, bent or molded?
Hot work 1050–870 °C then slow cool/anneal; cold forming limited to light bending or upsetting of spheroidized bar; harden by oil quench from 830–845 °C after preheat, temper immediately at 150–370 °C.
What is the maximum service temperature of L7?
L7 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between L7-ANN and L7 CD-ANN?
ANN is the default condition — standard stock condition for machining and forming before hardening. CD-ANN: use for close-tolerance shafting and gauge blanks that will be hardened after light machining. Yield strength is 415 MPa in ANN versus 620 MPa in CD-ANN.
How much does L7 cost?
L7 is a standard-cost steel ($$), cheaper than about 71% 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 (2015)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Special-Purpose Tool Steels) — ASM International (1990)
- ASM Specialty Handbook: Tool Materials — ASM International (1995)
- ASM Handbook Vol. 4: Heat Treating (tool steel hardening practice) — ASM International (1991)
- UNS T61207 alloy designation record — SAE/ASTM Unified Numbering System (2017)
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.