Steel M45 · heat-treated state
Steel M45 Q&T
Properties of the Q&T condition, compared with the other M45 tempers.
Toughness-biased hardening level for larger cutters, taps and broaches where chipping is the failure mode.
What is M45 Q&T?
M45 Q&T is M45 heat treated to Q&T — toughness-biased hardening level for larger cutters, taps and broaches where chipping is the failure mode. M45 Q&T 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 0.5% and the elastic modulus is 227 GPa (32.9 Msi). M45 Q&T 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; Q&T 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 — 78/100, better than 95% of steel grades
- High strength — 620 MPa (89.9 ksi), better than 78% of steel grades
Limitations
- Limited ductility — 0.5%, worse than 100% of steel grades
- Difficult to machine — 5/100, worse than 100% of steel grades
- Low fracture toughness — 17 MPa·√m (15.5 ksi·√in), worse than 99% of steel grades
- Difficult to weld — 10/100, worse than 99% of steel grades
- Limited formability — 8/100, worse than 97% of steel grades
M45 Q&T properties
Typical room-temperature values for M45 Q&T — 15 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 Q&T 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 Q&T 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 0.5% and the elastic modulus is 227 GPa (32.9 Msi).
Thermal6
M45 Q&T 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).
Electrical3
M45 Q&T 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 Q&T 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 Q&T's machinability is not recommended (5/100, worse than 100% of steel grades); weldability not recommended (10/100); 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 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 Q&T
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 Q&T — frequently asked
What is M45 Q&T used for?
M45 Q&T 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 Q&T?
M45 Q&T 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 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 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 Q&T be welded?
Not readily — weldability is rated not recommended (10/100). 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 Q&T?
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 Q&T 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 Q&T?
M45 Q&T 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 M45 Q&T?
Yes — M45 Q&T 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.