Steel M45 · heat-treated state
Steel M45 Hardened & Tempered
Properties of the Hardened & Tempered condition, compared with the other M45 tempers.
Maximum wear resistance and red hardness for drills, end mills and form tools cutting hard/heat-resistant alloys.
What is M45 Hardened & Tempered?
M45 Hardened & Tempered is M45 heat treated to Hardened & Tempered — maximum wear resistance and red hardness for drills, end mills and form tools cutting hard/heat-resistant alloys. M45 Hardened & Tempered 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 0% and the elastic modulus is 230 GPa (33.4 Msi). M45 Hardened & Tempered 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). Annealed is the default condition FabDigit quotes; Hardened & Tempered is available on request or by drawing note.
Advantages
- High service temperature — 620°C (1,148 °F), better than 99% 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
- Low fracture toughness — 13 MPa·√m (11.8 ksi·√in), worse than 100% of steel grades
- Difficult to machine — 4/100, worse than 100% of steel grades
- Difficult to weld — 8/100, worse than 100% of steel grades
- Limited formability — 2/100, worse than 100% of steel grades
M45 Hardened & Tempered properties
Typical room-temperature values for M45 Hardened & Tempered — 16 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 Hardened & Tempered 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 Hardened & Tempered 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 0% and the elastic modulus is 230 GPa (33.4 Msi).
Thermal6
M45 Hardened & Tempered is rated for continuous service to 620°C (1,148 °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 Hardened & Tempered 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 Hardened & Tempered 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 Hardened & Tempered's machinability is not recommended (4/100, worse than 100% of steel grades); weldability not recommended (8/100); formability not recommended (2/100).
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 Hardened & Tempered
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 Hardened & Tempered — frequently asked
What is M45 Hardened & Tempered used for?
M45 Hardened & Tempered 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 Hardened & Tempered?
M45 Hardened & Tempered 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 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 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 Hardened & Tempered be welded?
Not readily — weldability is rated not recommended (8/100). 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 Hardened & Tempered?
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 Hardened & Tempered 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 Hardened & Tempered?
M45 Hardened & Tempered is rated for continuous use to about 620°C (1,148 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in M45 Hardened & Tempered?
Yes — M45 Hardened & Tempered 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.