Steel M42 Q&T (Quenched and tempered)
Heat-treated state
AISI/SAE M42 · UNS T11342 · EN 1.3247, S2-10-1-8 · GB W2Mo9Cr4VCo8
Toughness-biased working hardness for larger cutters, punches and interrupted cutting.
Values for the Q&T condition
Other M42 tempers and conditions
M42 is listed in 3 conditions; see the grade overview at M42.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft annealed (spheroidized) supply condition | Standard mill supply condition for bar, plate and blanks — machine/grind to shape before hardening. | 620 | 900 | 12 | 25 HRC | 3.1 % IACS |
Maximum hardness | Pick for maximum wear resistance in small, rigidly supported tools (form tools, thread taps, razor/knife blades); very brittle. | 1,800 | 1,900 | 0 | 69 HRC | 2.6 % IACS |
Q&TThis page Quenched and tempered | Toughness-biased working hardness for larger cutters, punches and interrupted cutting. | 2,400 | 0 | 65 HRC | — |
What is M42 Q&T?
M42 Q&T is M42 heat treated to Q&T — toughness-biased working hardness for larger cutters, punches and interrupted cutting. M42 Q&T has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 78% of steel grades. Elongation at break is 0% and the elastic modulus is 222 GPa (32.2 Msi). M42 Q&T has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 94% of steel grades. It melts at 1,290°C (2,354 °F). Annealed is the default condition FabDigit quotes; Q&T is available on request or by drawing note.
Advantages
- High service temperature — 590°C (1,094 °F), better than 97% of steel grades
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- High strength — 620 MPa (89.9 ksi), better than 78% of steel grades
Limitations
- Limited ductility — 0%, worse than 100% of steel grades
- Difficult to machine — 5/100, worse than 100% of steel grades
- Low fracture toughness — 16 MPa·√m (14.6 ksi·√in), worse than 99% of steel grades
- Limited formability — 10/100, worse than 95% of steel grades
- High embodied carbon — 4.4 kg CO₂/kg, worse than 95% of steel grades
M42 Q&T properties
Typical room-temperature values for M42 Q&T; 12 are specific to this condition. Other listed values are M42 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
M42 Q&T has a density of 7.98 g/cm³ (0.288 lb/in³), heavier than 94% of steel grades. It melts at 1,290°C (2,354 °F).
Mechanical17
M42 Q&T has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 78% of steel grades. Elongation at break is 0% and the elastic modulus is 222 GPa (32.2 Msi).
Thermal5
M42 Q&T is rated for continuous service to 590°C (1,094 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical3
M42 Q&T conducts electricity at 3.1 % IACS, worse than 89% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of M42 Q&T takes about 62 MJ of energy and emits 4.4 kg of CO₂ — more than 96% of steel grades. Typical recycled content is 30%.
Manufacturability8
M42 Q&T's machinability is not recommended (5/100, worse than 100% of steel grades); weldability poor (20/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M42 Q&T
Is M42 easy to machine?
Machine only in the annealed state with rigid setups, low speeds and generous coolant; hardened M42 must be ground or EDM'd (grind with SG/CBN wheels, avoid burn and grinding cracks).
Can M42 be welded?
Not a weldable structural steel — repair-weld only with matched HSS/Co filler, 500–550 °C preheat and immediate re-temper to avoid cracking.
Can M42 be formed, bent or molded?
Hot work 1100→900 °C with slow controlled cooling; cold forming is impractical. Harden 1170–1190 °C (salt/vacuum), oil or gas quench, then temper 3× at 540–560 °C, 1 h each.
What surface finishes work on M42?
Not anodizable; use black oxide, steam tempering, phosphate or PVD TiN/TiAlN for wear and corrosion protection; oil-film protect all bare stock.
M42 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 |
|---|---|---|
| C | 1.05 – 1.15 | 1.1 |
| Si | 0.15 – 0.65 | 0.35 |
| Mn | 0.15 – 0.4 | 0.28 |
| Cr | 3.5 – 4.25 | 3.9 |
| Mo | 9 – 10 | 9.5 |
| W | 1.15 – 1.85 | 1.5 |
| V | 0.95 – 1.35 | 1.15 |
| Cogives red hardness | 7.75 – 8.75 | 8.25 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
M42 Q&T — frequently asked
What is M42 Q&T used for?
M42 Q&T is typically used for twist drills for high-strength alloy steel, end mills and milling cutters, taps and thread-cutting tools, form tools and cutting inserts, reamers and broaches and cold-work die punches. In short: ultimate cutting hardness.
What is the yield strength of M42 Q&T?
M42 Q&T has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 2,400 MPa (348 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is M42 Q&T easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% of steel grades). Machine only in the annealed state with rigid setups, low speeds and generous coolant; hardened M42 must be ground or EDM'd (grind with SG/CBN wheels, avoid burn and grinding cracks).
Can M42 Q&T be welded?
Not readily — weldability is rated poor (20/100). Not a weldable structural steel — repair-weld only with matched HSS/Co filler, 500–550 °C preheat and immediate re-temper to avoid cracking.
What surface finishes work on M42 Q&T?
Not anodizable; use black oxide, steam tempering, phosphate or PVD TiN/TiAlN for wear and corrosion protection; oil-film protect all bare stock.
Can M42 Q&T be formed, bent or molded?
Hot work 1100→900 °C with slow controlled cooling; cold forming is impractical. Harden 1170–1190 °C (salt/vacuum), oil or gas quench, then temper 3× at 540–560 °C, 1 h each.
What is the maximum service temperature of M42 Q&T?
M42 Q&T is rated for continuous use to about 590°C (1,094 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in M42 Q&T?
Yes — M42 Q&T is available for CNC machining; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A600 — Tool Steel High Speed Tool Steels — ASTM International (2021)
- EN ISO 4957 — Tool steels (1.3247 / HS2-9-1-8) — ISO/CEN (2018)
- GB/T 9943 — (W2Mo9Cr4VCo8) — SAC (2008)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Specialty Handbook — Tool Materials — ASM International (1995)
- Böhler S500 (M42) high speed steel datasheet — voestalpine Böhler Edelstahl (2022)
- Erasteel ASP/HSS grade data (M42) — Erasteel (2021)
- M42/W2Mo9Cr4VCo8 (2025)
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.