Steel M42 · temper · default condition
Steel M42 Annealed
Properties of the Annealed condition, compared with the other M42 tempers.
Standard mill supply condition for bar, plate and blanks — machine/grind to shape before hardening.
What is M42 Annealed?
M42 Annealed is M42 in the Annealed temper — standard mill supply condition for bar, plate and blanks — machine/grind to shape before hardening. M42 Annealed has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 78% of steel grades. Elongation at break is 12% and the elastic modulus is 224 GPa (32.5 Msi). M42 Annealed 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).
Advantages
- 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 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
- Difficult to weld — 15/100, worse than 91% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
M42 Annealed properties
Typical room-temperature values for M42 Annealed — 9 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 Annealed 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 Annealed has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 78% of steel grades. Elongation at break is 12% and the elastic modulus is 224 GPa (32.5 Msi).
Thermal5
M42 Annealed is rated for continuous service to 400°C (752 °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 Annealed 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 Annealed 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 Annealed's machinability is fair (38/100, worse than 80% of steel grades); weldability poor (15/100); formability not recommended (8/100).
Common Calculations5
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 Annealed
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 Annealed — frequently asked
What is M42 Annealed used for?
M42 Annealed 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 Annealed?
M42 Annealed has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is M42 Annealed easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% 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 Annealed 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 Annealed?
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 Annealed 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 Annealed?
M42 Annealed is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in M42 Annealed?
Yes — M42 Annealed 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.