Steel M42 · heat-treated state
Steel M42 Hardened & Tempered
Properties of the Hardened & Tempered condition, compared with the other M42 tempers.
Usual finished hardness for M42 drills, taps, end mills and inserts cutting hard or gummy alloys.
What is M42 Hardened & Tempered?
M42 Hardened & Tempered is M42 heat treated to Hardened & Tempered — usual finished hardness for M42 drills, taps, end mills and inserts cutting hard or gummy alloys. M42 Hardened & Tempered has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 78% of steel grades. Elongation at break is 0% and the elastic modulus is 224 GPa (32.5 Msi). M42 Hardened & Tempered 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; Hardened & Tempered is available on request or by drawing note.
Advantages
- High service temperature — 600°C (1,112 °F), better than 98% 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 — 4/100, worse than 100% of steel grades
- Limited formability — 8/100, worse than 97% of steel grades
- High embodied carbon — 4.4 kg CO₂/kg, worse than 95% of steel grades
- Poor heat conductor — 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades
M42 Hardened & Tempered properties
Typical room-temperature values for M42 Hardened & Tempered — 11 properties are specific to this condition; the rest are grade-level values shared by every M42 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
M42 Hardened & Tempered 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).
Mechanical12
M42 Hardened & Tempered has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 78% of steel grades. Elongation at break is 0% and the elastic modulus is 224 GPa (32.5 Msi).
Thermal5
M42 Hardened & Tempered is rated for continuous service to 600°C (1,112 °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).
Electrical2
M42 Hardened & Tempered has an electrical resistivity of 5.5×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of M42 Hardened & Tempered 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 Hardened & Tempered's machinability is not recommended (4/100, worse than 100% of steel grades); weldability poor (15/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other M42 tempers and conditions
M42 is also supplied in 4 other conditions. The full side-by-side table is on the M42 overview.
- AnnealedDefaultStandard mill supply condition for bar, plate and blanks — machine/grind to shape before hardening.620 MPa yield · 25 HRC
- Q&TToughness-biased working hardness for larger cutters, punches and interrupted cutting.2,400 MPa tensile
- Hardened & TemperedUsual finished hardness for M42 drills, taps, end mills and inserts cutting hard or gummy alloys.2,200 MPa tensile
- H&T 68-70 HRCPick for maximum wear resistance in small, rigidly supported tools (form tools, thread taps, razor/knife blades); very brittle.1,900 MPa tensile
Working with M42 Hardened & Tempered
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 Hardened & Tempered — frequently asked
What is M42 Hardened & Tempered used for?
M42 Hardened & Tempered 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 Hardened & Tempered?
M42 Hardened & Tempered has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is M42 Hardened & Tempered easy to machine?
Not especially — machinability is rated not recommended (4/100, 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 Hardened & Tempered be welded?
Not readily — weldability is rated poor (15/100). 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 Hardened & Tempered?
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 Hardened & Tempered 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 Hardened & Tempered?
M42 Hardened & Tempered is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in M42 Hardened & Tempered?
Yes — M42 Hardened & Tempered is available for CNC machining with instant online pricing. 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.