Steel L7 NORM
Heat-treated state
AISI/SAE L7 · UNS T61207
NORM = normalized
Intermediate grain-refining step before spheroidizing or hardening of forged sections.
Values for the NORM condition
Other L7 tempers and conditions
L7 is listed in 9 conditions; see the grade overview at L7.
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 |
NORMThis page 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 NORM?
L7 NORM is L7 heat treated to NORM — intermediate grain-refining step before spheroidizing or hardening of forged sections. L7 NORM has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 73% of steel grades. Elongation at break is 12% and the elastic modulus is 207 GPa (30 Msi). L7 NORM 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). ANN is the default condition FabDigit quotes; NORM is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Difficult to weld — 12/100, worse than 96% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Limited formability — 12/100, worse than 92% of steel grades
- Difficult to machine — 30/100, worse than 89% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
L7 NORM properties
Typical room-temperature values for L7 NORM; 22 are specific to this condition. Other listed values are L7 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
L7 NORM 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 NORM has a yield strength of 560 MPa (81.2 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 73% of steel grades. Elongation at break is 12% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
L7 NORM is rated for continuous service to 200°C (392 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
L7 NORM conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of L7 NORM 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 NORM's machinability is poor (30/100, worse than 89% of steel grades); weldability not recommended (12/100); formability not recommended (12/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with L7 NORM
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.
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.
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 | — |
L7 NORM — frequently asked
What is L7 NORM used for?
L7 NORM 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 NORM?
L7 NORM has a typical yield strength of 560 MPa (81.2 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 73% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is L7 NORM easy to machine?
Not especially — machinability is rated poor (30/100, worse than 89% 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 NORM be welded?
Not readily — weldability is rated not recommended (12/100). 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 NORM?
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 NORM 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 NORM?
L7 NORM is rated for continuous use to about 200°C (392 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.