Steel M43
AISI/SAE M43 · UNS T11343
M43 is a semi-processed non-oriented silicon steel to ASTM A683 (UNS T11343), punched in the as-delivered condition and then annealed by the customer at 790–840 °C in a decarburising atmosphere to develop final core loss and permeability.
Reference datasheet — M43 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the SP condition
M43 tempers and conditions
M43 is supplied in 5 conditions, soft to hard. SP is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Quality (decarburising/grain-growth) annealed after punching | Condition after the ~790–840 °C customer anneal — pick when magnetic performance (core loss ≈ 4.3 W/lb at 1.5 T, 60 Hz) is the design driver. | 270 | 420 | 30 | 110 HB | 4.1 % IACS |
SPDefault Semi-processed, as-rolled | Standard stocked condition for stamped lamination stacks: punch first, then anneal to develop core loss. | 315 | 450 | 20 | 130 HB | 4.1 % IACS |
Annealed | As-supplied soft bar of the M43 high-speed steel (≈1.2C-8Mo-8Co-3.75Cr-1.6V-2.75W) for machining tool blanks before hardening. | 600 | 900 | 10 | 24 HRC | 22 W/m·K |
Hardened & triple tempered | Maximum-hardness condition (≈1190–1210 °C austenitise, 540–560 °C triple temper) for drills, end mills and form tools cutting high-strength or abrasive alloys. | 2,100 | 0.5 | 68 HRC | 24 W/m·K | |
Hardened & tempered | Slightly softer temper for interrupted cuts, taps and broaches where edge chipping is the failure mode. | 2,100 | 2,350 | 0.5 | 66 HRC | 3.1 % IACS |
What is M43?
M43 is a semi-processed non-oriented silicon steel to ASTM A683 (UNS T11343), punched in the as-delivered condition and then annealed by the customer at 790–840 °C in a decarburising atmosphere to develop final core loss and permeability. Stampers choose it for high-volume lamination stacks in small and appliance motors, where that same anneal also relieves punching stress. It needs in-house annealing capacity and is limited to about 200 °C in service; fully processed M19 or M27 avoids the step. The designation is also used for a high-speed steel, so confirm the standard when ordering. M43 has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,490°C (2,714 °F). M43 has a yield strength of 315 MPa (45.7 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 82% of steel grades. Elongation at break is 20% and the elastic modulus is 200 GPa (29 Msi).
What is M43 used for?
- Small motor lamination stacks
- Appliance motor stators and rotors
- Fractional-horsepower motor cores
- Solenoid and relay laminations
- Ballast and small transformer cores
- Cutting and form tools (high-speed steel variant)
Advantages
- Forms and bends easily — 65/100, better than 81% of steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Poor heat conductor — 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades
- Low electrical conductivity — 4.1 % IACS, worse than 83% of steel grades
- Low strength — 315 MPa (45.7 ksi), worse than 82% of steel grades
M43 properties
Typical room-temperature values for M43-SP; bars are the position among steel grades.
Physical3
M43 has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,490°C (2,714 °F).
Mechanical12
M43 has a yield strength of 315 MPa (45.7 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 82% of steel grades. Elongation at break is 20% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
M43 is rated for continuous service to 200°C (392 °F). It conducts heat at 27 W/m·K (15.6 BTU/hr·ft·°F), worse than 86% of steel grades. Thermal expansion is 11.6 µm/m·K (6.44 µin/in·°F).
Electrical3
M43 conducts electricity at 4.1 % IACS, worse than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of M43 takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 30%.
Manufacturability7
M43's machinability is fair (45/100, worse than 65% of steel grades); weldability good (55/100); formability good (65/100).
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. M43 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with M43
Is M43 easy to machine?
Electrical-steel form is best blanked/punched with carbide dies (Si is abrasive, burr control critical); the HSS form must be machined in the annealed state and finished by grinding after hardening.
Can M43 be welded?
Avoid welding through electrical laminations — the HAZ loses permeability and raises core loss; HSS M43 is only welded by careful preheated TIG/laser repair on cutting edges.
Can M43 be formed, bent or molded?
Semi-processed sheet punches and stacks well, then requires a 790–840 °C anneal in a decarburising atmosphere to develop core loss; HSS is forged 1050–1150 °C then slow annealed at 870–900 °C.
M43 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 |
|---|---|---|
| CA683 Type M43 electrical steel: chemistry not specified by the standard; typical mill analysis | ≤ 0.03 | 0.02 |
| Siprimary resistivity/loss control element | 1.7 – 2.5 | 2.1 |
| Al | 0.15 – 0.5 | 0.3 |
| Mn | 0.15 – 0.5 | 0.3 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.02 | 0.01 |
| Fe | balance |
What surface finishes work on M43?
Laminations rely on the mill C-3/C-5 insulating coating or dip varnish for interlaminar resistance; HSS tools are typically steam-oxide, nitride or TiN/TiAlN coated.
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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel M43 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T11343
How much does M43 cost?
M43 is a budget-cost steel ($), cheaper than about 90% 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.
M43 — frequently asked
What is M43 used for?
M43 is typically used for small motor lamination stacks, appliance motor stators and rotors, fractional-horsepower motor cores, solenoid and relay laminations, ballast and small transformer cores and cutting and form tools (high-speed steel variant). In short: semi-processed lamination steel; requires customer anneal; low-cost stamping grade.
What is the yield strength of M43?
M43 has a typical yield strength of 315 MPa (45.7 ksi) and a tensile strength of 450 MPa (65.3 ksi) — weaker than 82% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is M43 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Electrical-steel form is best blanked/punched with carbide dies (Si is abrasive, burr control critical); the HSS form must be machined in the annealed state and finished by grinding after hardening.
Can M43 be welded?
Yes — weldability is rated good (55/100). Avoid welding through electrical laminations — the HAZ loses permeability and raises core loss; HSS M43 is only welded by careful preheated TIG/laser repair on cutting edges.
What surface finishes work on M43?
Laminations rely on the mill C-3/C-5 insulating coating or dip varnish for interlaminar resistance; HSS tools are typically steam-oxide, nitride or TiN/TiAlN coated.
Can M43 be formed, bent or molded?
Semi-processed sheet punches and stacks well, then requires a 790–840 °C anneal in a decarburising atmosphere to develop core loss; HSS is forged 1050–1150 °C then slow annealed at 870–900 °C.
What is the maximum service temperature of M43?
M43 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.
What is the difference between M43-SP and M43 HSS-A?
SP is the default condition — standard stocked condition for stamped lamination stacks: punch first, then anneal to develop core loss. HSS-A: as-supplied soft bar of the M43 high-speed steel (≈1.2C-8Mo-8Co-3.75Cr-1.6V-2.75W) for machining tool blanks before hardening. Yield strength is 315 MPa in SP versus 600 MPa in HSS-A.
How much does M43 cost?
M43 is a budget-cost steel ($), cheaper than about 90% 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.
Sources
- ASTM A683 — Nonoriented Electrical Steel, Semiprocessed Types — ASTM International (2019)
- ASTM A677 — Fully Processed Nonoriented Electrical Steel — ASTM International (2019)
- ASTM A600 / SAE J438 — High-Speed Tool Steels (M43, UNS T11343) — ASTM International / SAE (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Specialty Handbook — Tool Materials — ASM International (1995)
- Non-oriented electrical steel lamination datasheets (M-grade core loss/mechanical data) — Cleveland-Cliffs (AK Steel) (2021)
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.