Steel M45
AISI/SAE M45
M45 is a semi-processed, low-silicon non-oriented electrical steel supplied to ASTM A683 as coil and sheet for economical motor and transformer cores.
Values for the Annealed condition
M45 tempers and conditions
M45 is supplied in 4 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
peak hardness 67–69 HRC (1190–1210 °C, 3×540–550 °C) | Maximum wear resistance and red hardness for drills, end mills and form tools cutting hard/heat-resistant alloys. | 0 | 68 HRC | — | ||
AnnealedDefault spheroidize annealed bar/blank stock | Standard supply condition for bar, blanks and preforms; soft enough to turn, mill and drill before hardening. | 620 | 950 | 12 | 26 HRC | — |
H&T + Plasma/Salt-bath Nitrided surface | Low-temperature surface treatment for extra abrasion and galling resistance on taps, hobs and gear cutters; case is brittle so use thin layers. | 2,000 | 2,250 | 0.5 | 68 HRC | 3 % IACS |
H&T + Deep Cryogenic Treatment | Choose when dimensional stability and retained-austenite removal matter (precision gauges, long broaches, fine-pitch taps). | 2,050 | 2,300 | 0.5 | 69 HRC | 3 % IACS |
Supply forms, finishes and certifications
Ways M45 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
H&T+PVD | H&T + PVD coated | Surface finish |
What is M45?
M45 is a semi-processed, low-silicon non-oriented electrical steel supplied to ASTM A683 as coil and sheet for economical motor and transformer cores. The user stamps the laminations and then decarburize-anneals them to develop the final magnetic properties, which lowers material cost relative to fully processed grades. It is not a structural or corrosion-resistant material: service is limited to about 200 °C, formability and machinability are poor, and unprotected surfaces must be oiled. Fully processed non-oriented grades are the alternative when in-house annealing is not available. M45 has a density of 8.1 g/cm³ (0.293 lb/in³), heavier than 97% of steel grades. It melts at 1,260°C (2,300 °F). M45 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).
What is M45 used for?
- Motor stator and rotor laminations
- Distribution transformer cores
- Small generator cores
- Solenoid and relay cores
- Reactor and ballast laminations
- Pole pieces and magnetic shunts
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 95% 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 properties
Typical room-temperature values for M45-Annealed; bars are the position among steel grades.
Physical3
M45 has a density of 8.1 g/cm³ (0.293 lb/in³), heavier than 97% of steel grades. It melts at 1,260°C (2,300 °F).
Mechanical16
M45 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 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 conducts electricity at 3.2 % IACS, worse than 87% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of M45 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'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.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. M45 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with M45
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.
Manufacturability
The process limits FabDigit applies to M45. Every M45 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
Sheet metal
| Formability | Better8 / 100 |
|---|---|
| Weldability | Poor15 / 100 |
| Bendable | Yes |
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 |
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.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Black / Phosphate
Thermal Spray
How much does M45 cost?
M45 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
M45 — frequently asked
What is M45 used for?
M45 is typically used for motor stator and rotor laminations, distribution transformer cores, small generator cores, solenoid and relay cores, reactor and ballast laminations and pole pieces and magnetic shunts. In short: non-oriented electrical coil.
What is the yield strength of M45?
M45 has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 4 listed tempers.
Is M45 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Machine only in the annealed condition with rigid setups, cobalt or carbide tooling and flood coolant; after hardening the part can only be ground (soft SG/CBN wheels, light infeed to avoid grinding burn) or EDM'd.
Can M45 be welded?
Not readily — weldability is rated poor (15/100). Not a structural weld metal — repair only by TIG/laser with matching HSS filler at 500–550 °C preheat followed immediately by a full triple temper; expect microcracking otherwise.
What surface finishes work on M45?
Black oxide, steam-oxide or nitride for anti-galling; TiN/TiCN/TiAlN PVD at ≤500 °C is standard for cutting tools; unprotected surfaces must be oiled since the 4 % Cr gives no real corrosion resistance.
Can M45 be formed, bent or molded?
Hot work 1050–900 °C with slow furnace cooling to the spheroidized state; cold forming is not practical, and blanks must be finished by machining or grinding.
What is the maximum service temperature of M45?
M45 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does M45 cost?
M45 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in M45?
Yes — M45 is available for sheet metal; every part is priced by an engineer rather than instantly. 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.