Steel M45 · temper · default condition
Steel M45 Annealed
Properties of the Annealed condition, compared with the other M45 tempers.
Standard supply condition for bar, blanks and preforms; soft enough to turn, mill and drill before hardening.
What is M45 Annealed?
M45 Annealed is M45 in the Annealed temper — standard supply condition for bar, blanks and preforms; soft enough to turn, mill and drill before hardening. M45 Annealed has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 78% of steel grades. Elongation at break is 12% and the elastic modulus is 217 GPa (31.5 Msi). M45 Annealed has a density of 8.1 g/cm³ (0.293 lb/in³), heavier than 96% of steel grades. It melts at 1,260°C (2,300 °F).
Advantages
- Polishes to a fine finish — 75/100, better than 94% 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
- Low fracture toughness — 30 MPa·√m (27.3 ksi·√in), worse than 96% of steel grades
- High embodied carbon — 4.2 kg CO₂/kg, worse than 94% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Poor heat conductor — 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades
M45 Annealed properties
Typical room-temperature values for M45 Annealed — 14 properties are specific to this condition; the rest are grade-level values shared by every M45 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
M45 Annealed has a density of 8.1 g/cm³ (0.293 lb/in³), heavier than 96% of steel grades. It melts at 1,260°C (2,300 °F).
Mechanical16
M45 Annealed has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 78% of steel grades. Elongation at break is 12% and the elastic modulus is 217 GPa (31.5 Msi).
Thermal6
M45 Annealed is rated for continuous service to 200°C (392 °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
M45 Annealed conducts electricity at 3.2 % IACS, worse than 88% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of M45 Annealed takes about 55 MJ of energy and emits 4.2 kg of CO₂ — more than 94% of steel grades. Typical recycled content is 35%.
Manufacturability7
M45 Annealed's machinability is poor (25/100, worse than 93% 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 M45 tempers and conditions
M45 is also supplied in 5 other conditions. The full side-by-side table is on the M45 overview.
- AnnealedDefaultStandard supply condition for bar, blanks and preforms; soft enough to turn, mill and drill before hardening.620 MPa yield · 26 HRC
- Q&TToughness-biased hardening level for larger cutters, taps and broaches where chipping is the failure mode.65 HRC
- Hardened & TemperedMaximum wear resistance and red hardness for drills, end mills and form tools cutting hard/heat-resistant alloys.68 HRC
Working with M45 Annealed
Is M45 easy to machine?
Machine only in the annealed condition with rigid setups, cobalt or carbide tooling and flood coolant; after hardening the part can only be ground (soft SG/CBN wheels, light infeed to avoid grinding burn) or EDM'd.
Can M45 be welded?
Not a structural weld metal — repair only by TIG/laser with matching HSS filler at 500–550 °C preheat followed immediately by a full triple temper; expect microcracking otherwise.
Can M45 be formed, bent or molded?
Hot work 1050–900 °C with slow furnace cooling to the spheroidized state; cold forming is not practical, and blanks must be finished by machining or grinding.
What surface finishes work on M45?
Black oxide, steam-oxide or nitride for anti-galling; TiN/TiCN/TiAlN PVD at ≤500 °C is standard for cutting tools; unprotected surfaces must be oiled since the 4 % Cr gives no real corrosion resistance.
M45 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 to form MC/M6C carbides | 1.25 – 1.4 | 1.3 |
| W | 8 – 9 | 8.5 |
| Mo | 4.75 – 5.5 | 5.1 |
| Cr | 3.75 – 4.5 | 4.1 |
| V | 1.6 – 2.05 | 1.8 |
| Coraises hot hardness / red hardness | 5 – 5.5 | 5.2 |
| Mn | 0.15 – 0.4 | 0.28 |
| Si | 0.15 – 0.65 | 0.35 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Febalance; composition per ASM high-speed-steel tables — verify against mill certificate, M45 is a low-volume super-HSS grade | balance | — |
M45 Annealed — frequently asked
What is M45 Annealed used for?
M45 Annealed is typically used for motor stator and rotor laminations, distribution transformer cores, small generator cores, solenoid and relay cores, reactor and ballast laminations and pole pieces and magnetic shunts. In short: non-oriented electrical coil.
What is the yield strength of M45 Annealed?
M45 Annealed has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is M45 Annealed easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Machine only in the annealed condition with rigid setups, cobalt or carbide tooling and flood coolant; after hardening the part can only be ground (soft SG/CBN wheels, light infeed to avoid grinding burn) or EDM'd.
Can M45 Annealed be welded?
Not readily — weldability is rated poor (15/100). Not a structural weld metal — repair only by TIG/laser with matching HSS filler at 500–550 °C preheat followed immediately by a full triple temper; expect microcracking otherwise.
What surface finishes work on M45 Annealed?
Black oxide, steam-oxide or nitride for anti-galling; TiN/TiCN/TiAlN PVD at ≤500 °C is standard for cutting tools; unprotected surfaces must be oiled since the 4 % Cr gives no real corrosion resistance.
Can M45 Annealed be formed, bent or molded?
Hot work 1050–900 °C with slow furnace cooling to the spheroidized state; cold forming is not practical, and blanks must be finished by machining or grinding.
What is the maximum service temperature of M45 Annealed?
M45 Annealed is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in M45 Annealed?
Yes — M45 Annealed is available for sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys (tool steel chapter) — ASM International (1990)
- Tool Steels, 5th ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- ASTM A600 — Tool Steel High Speed Tool Steels — ASTM (2016)
- Cobalt super-HSS grade datasheets (M42/M35 class) — Böhler / Erasteel (2022)
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.