Steel L6 Q&T 42-46 HRC
Hardness band
AISI/SAE L6 · UNS T61206
Q&T 42-46 HRC = oil quenched from 845–870 °C, tempered ~510–540 °C
Maximum-toughness setting for heavy shock tooling, forging die inserts and large punches.
Values for the Q&T 42-46 HRC condition
Other L6 tempers and conditions
L6 is listed in 6 conditions; see the grade overview at L6.
- A
- PH 34-38 HRC
- Q&T 42-46 HRC
- Q&T 50-54 HRC
- Q&T 54-58 HRC
- Q&T 58-62 HRC
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 | — |
Q&T 42-46 HRCThis page 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 Q&T 42-46 HRC?
L6 Q&T 42-46 HRC is L6 heat treated to Q&T 42-46 HRC — maximum-toughness setting for heavy shock tooling, forging die inserts and large punches. L6 Q&T 42-46 HRC has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,420 MPa (206 ksi) — stronger than 95% of steel grades. Elongation at break is 10% and the elastic modulus is 207 GPa (30 Msi). L6 Q&T 42-46 HRC 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). A is the default condition FabDigit quotes; Q&T 42-46 HRC is available on request or by drawing note.
Advantages
- High strength — 1,250 MPa (181 ksi), better than 95% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to weld — 10/100, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Difficult to machine — 25/100, worse than 93% of steel grades
- Limited ductility — 10%, worse than 91% of steel grades
L6 Q&T 42-46 HRC properties
Typical room-temperature values for L6 Q&T 42-46 HRC; 17 are specific to this condition. Other listed values are L6 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
L6 Q&T 42-46 HRC 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 Q&T 42-46 HRC has a yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,420 MPa (206 ksi) — stronger than 95% of steel grades. Elongation at break is 10% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
L6 Q&T 42-46 HRC is rated for continuous service to 450°C (842 °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 Q&T 42-46 HRC 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 Q&T 42-46 HRC 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 Q&T 42-46 HRC's machinability is poor (25/100, worse than 93% of steel grades); weldability not recommended (10/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with L6 Q&T 42-46 HRC
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.
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.
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 | — |
L6 Q&T 42-46 HRC — frequently asked
What is L6 Q&T 42-46 HRC used for?
L6 Q&T 42-46 HRC 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 Q&T 42-46 HRC?
L6 Q&T 42-46 HRC has a typical yield strength of 1,250 MPa (181 ksi) and a tensile strength of 1,420 MPa (206 ksi) — stronger than 95% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is L6 Q&T 42-46 HRC easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% 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 Q&T 42-46 HRC be welded?
Not readily — weldability is rated not recommended (10/100). 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 Q&T 42-46 HRC?
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 Q&T 42-46 HRC 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 Q&T 42-46 HRC?
L6 Q&T 42-46 HRC is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.