Steel L7 QT-60-62HRC
Hardness band
AISI/SAE L7 · UNS T61207
QT-60-62HRC = 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.
Values for the QT-60-62HRC 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 |
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 | — |
QT-60-62HRCThis page 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 QT-60-62HRC?
L7 QT-60-62HRC is L7 heat treated to QT-60-62HRC — maximum hardness/wear for gauge blocks and light-duty cutting or burnishing tools; lowest toughness. L7 QT-60-62HRC has a yield strength of 2,050 MPa (297 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 100% of steel grades. Elongation at break is 1% and the elastic modulus is 207 GPa (30 Msi). L7 QT-60-62HRC 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; QT-60-62HRC is available on request or by drawing note.
Advantages
- High strength — 2,050 MPa (297 ksi), better than 100% of steel grades
- Polishes to a fine finish — 80/100, better than 97% of steel grades
Limitations
- Difficult to machine — 5/100, worse than 100% of steel grades
- Limited ductility — 1%, worse than 99% of steel grades
- Limited service temperature — 150°C (302 °F), worse than 99% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Poor heat conductor — 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades
L7 QT-60-62HRC properties
Typical room-temperature values for L7 QT-60-62HRC; 14 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 QT-60-62HRC 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 QT-60-62HRC has a yield strength of 2,050 MPa (297 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 100% of steel grades. Elongation at break is 1% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
L7 QT-60-62HRC is rated for continuous service to 150°C (302 °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 QT-60-62HRC 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 QT-60-62HRC 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 QT-60-62HRC's machinability is not recommended (5/100, worse than 100% of steel grades); weldability poor (15/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with L7 QT-60-62HRC
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 QT-60-62HRC — frequently asked
What is L7 QT-60-62HRC used for?
L7 QT-60-62HRC 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 QT-60-62HRC?
L7 QT-60-62HRC has a typical yield strength of 2,050 MPa (297 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 100% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is L7 QT-60-62HRC easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% 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 QT-60-62HRC 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 QT-60-62HRC?
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 QT-60-62HRC 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 QT-60-62HRC?
L7 QT-60-62HRC is rated for continuous use to about 150°C (302 °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.