Steel M33
AISI/SAE M33 · UNS T11333
M33 (UNS T11333) is a high-cobalt molybdenum high-speed steel that provides hot hardness for the most severe high-speed machining conditions.
Reference datasheet — M33 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 ANN condition
M33 tempers and conditions
M33 is supplied in 3 conditions, soft to hard. ANN is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ANNDefault Annealed | Standard stock condition for bar, blanks and preforms; machine or grind to shape before hardening. | 550 | 880 | 20 | 240 HB | — |
Hardened & triple tempered | General working condition for cutting tools: best balance of red hardness and residual toughness. | 1,950 | 2,150 | 1 | 64 HRC | 23 W/m·K |
Hardened & tempered to maximum hardness | Pick for maximum hot hardness and wear life on abrasive/high-speed work where edge chipping risk is acceptable. | 2,250 | 0.5 | 66 HRC | — |
Supply forms, finishes and certifications
Ways M33 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
HT+SURF | Hardened + surface treated | Surface finish |
What is M33?
M33 (UNS T11333) is a high-cobalt molybdenum high-speed steel that provides hot hardness for the most severe high-speed machining conditions. It is stocked annealed as bar and blanks and heat treated to 63–65 or 65–67 HRC, with surface-treated options for coated tooling. Annealed properties are 880 MPa tensile, 550 MPa yield, 20 % elongation, 240 HB and 215 GPa modulus, with service to 500 °C. The cobalt content reduces toughness and increases cost relative to M2 or M30, and with 4 % Cr the steel has no corrosion resistance (score 16); M34 is the nearest alternative for higher-temperature work. M33 has a density of 8.03 g/cm³ (0.29 lb/in³), heavier than 96% of steel grades. It melts at 1,230°C (2,246 °F). M33 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 71% of steel grades. Elongation at break is 20% and the elastic modulus is 215 GPa (31.2 Msi).
What is M33 used for?
- High-speed turning
- Hard alloy machining
- Heavy interrupted cuts
Advantages
- Polishes to a fine finish — 78/100, better than 95% of steel grades
- High service temperature — 500°C (932 °F), better than 90% of steel grades
Limitations
- High embodied carbon — 4.6 kg CO₂/kg, worse than 96% of steel grades
- Poor heat conductor — 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades
- Low fracture toughness — 40 MPa·√m (36.4 ksi·√in), worse than 92% of steel grades
- Low electrical conductivity — 3 % IACS, worse than 91% of steel grades
- Difficult to weld — 18/100, worse than 87% of steel grades
M33 properties
Typical room-temperature values for M33-ANN; bars are the position among steel grades.
Physical3
M33 has a density of 8.03 g/cm³ (0.29 lb/in³), heavier than 96% of steel grades. It melts at 1,230°C (2,246 °F).
Mechanical16
M33 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 71% of steel grades. Elongation at break is 20% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
M33 is rated for continuous service to 500°C (932 °F). It conducts heat at 22 W/m·K (12.7 BTU/hr·ft·°F), worse than 93% of steel grades. Thermal expansion is 10.6 µm/m·K (5.89 µin/in·°F).
Electrical3
M33 conducts electricity at 3 % IACS, worse than 91% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (16/100), better than 79% of steel grades.
Sustainability4
Producing a kilogram of M33 takes about 62 MJ of energy and emits 4.6 kg of CO₂ — more than 96% of steel grades. Typical recycled content is 35%.
Manufacturability8
M33's machinability is fair (38/100, worse than 80% of steel grades); weldability poor (18/100); formability poor (15/100).
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. M33 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with M33
Is M33 easy to machine?
Machine only in the annealed condition with rigid setups, sharp cobalt-HSS or coated carbide, low speeds and generous coolant; after hardening it is a grind-only material (soft, friable CBN/SG wheels, avoid grinding burn).
Can M33 be welded?
Not a structural weld metal — repair only, with 500–550 °C preheat, matching HSS filler, and immediate re-temper at 550 °C to avoid quench cracking.
Can M33 be formed, bent or molded?
No cold forming; hot work between about 1100 °C and 900 °C followed by slow furnace cooling and full spheroidize anneal (860–900 °C, 15–25 °C/h to 700 °C).
M33 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 |
|---|---|---|
| C | 0.85 – 0.92 | 0.89 |
| Mn | 0.15 – 0.4 | 0.28 |
| Si | 0.15 – 0.5 | 0.3 |
| Cr | 3.5 – 4 | 3.75 |
| Mo | 9 – 10 | 9.5 |
| W | 1.3 – 2.1 | 1.7 |
| V | 1 – 1.35 | 1.15 |
| Coprovides hot hardness | 7.75 – 8.75 | 8.25 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on M33?
Cannot be anodized; use steam oxide, black oxide, nitriding or PVD TiN/TiAlN over a fine-ground surface, and oil/VCI-wrap for storage since the 4% Cr gives no rust protection.
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 M33 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T11333
How much does M33 cost?
M33 is a high-cost steel ($$$$), pricier than about 78% 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.
M33 — frequently asked
What is M33 used for?
M33 is typically used for high-speed turning, hard alloy machining and heavy interrupted cuts. In short: high-cobalt hot hardness; 500 °C service rating; for severe high-speed cutting.
What is the yield strength of M33?
M33 has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 71% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is M33 easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% of steel grades). Machine only in the annealed condition with rigid setups, sharp cobalt-HSS or coated carbide, low speeds and generous coolant; after hardening it is a grind-only material (soft, friable CBN/SG wheels, avoid grinding burn).
Can M33 be welded?
Not readily — weldability is rated poor (18/100). Not a structural weld metal — repair only, with 500–550 °C preheat, matching HSS filler, and immediate re-temper at 550 °C to avoid quench cracking.
What surface finishes work on M33?
Cannot be anodized; use steam oxide, black oxide, nitriding or PVD TiN/TiAlN over a fine-ground surface, and oil/VCI-wrap for storage since the 4% Cr gives no rust protection.
Can M33 be formed, bent or molded?
No cold forming; hot work between about 1100 °C and 900 °C followed by slow furnace cooling and full spheroidize anneal (860–900 °C, 15–25 °C/h to 700 °C).
What is the maximum service temperature of M33?
M33 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between M33-ANN and M33 HT63-65?
ANN is the default condition — standard stock condition for bar, blanks and preforms; machine or grind to shape before hardening. HT63-65: general working condition for cutting tools: best balance of red hardness and residual toughness. Yield strength is 550 MPa in ANN versus 1,950 MPa in HT63-65.
How much does M33 cost?
M33 is a high-cost steel ($$$$), pricier than about 78% 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 A600 — Standard Specification for Tool Steel High Speed — ASTM International (2016)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Tool Steels) — ASM International (1990)
- ASM Handbook Vol.16: Machining — ASM International (1989)
- Tool Steels, 5th ed. (Roberts, Krauss, Kennedy) — ASM International (1998)
- High-speed steel grade datasheets (M-series, cobalt grades) — Erasteel / Böhler / Crucible (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.