Steel M48
AISI/SAE M48 · UNS T11348
M48 (T11348) is a high-cobalt (about 9–10 % Co) molybdenum-type high-speed steel offering exceptional red hardness and wear resistance for the most demanding high-temperature cutting.
Reference datasheet — M48 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
M48 tempers and conditions
M48 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 | The as-supplied condition for bar, blanks and forgings — soft enough to machine tool geometry before hardening. | 620 | 950 | 10 | 26 HRC | 23 W/m·K |
Hardened & triple tempered | Standard cutting-tool condition: austenitize ~1200-1220 °C, quench, triple temper ~540-560 °C for maximum hot hardness and wear life. | 2,100 | 0 | 68 HRC | — | |
Hardened & triple tempered | Pick when some edge toughness is needed (interrupted cuts, larger cutters) at slightly reduced red hardness. | 2,300 | 0 | 66 HRC | — |
Supply forms, finishes and certifications
Ways M48 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
HT68-PVD | Hardened 67-69 HRC + PVD coating | Surface finish |
What is M48?
M48 (T11348) is a high-cobalt (about 9–10 % Co) molybdenum-type high-speed steel offering exceptional red hardness and wear resistance for the most demanding high-temperature cutting. Annealed bar is about 269 HB / 26 HRC with 950 MPa tensile, 620 MPa yield, 10 % elongation and 23 W/m·K; hardened conditions of 65 and 68 HRC are on file, including a PVD-coated variant, with service to roughly 500 °C. Machinability is the lowest of the group (score 25) and formability is limited (20), so blanks are machined annealed and finished by grinding or EDM. M41 or M44 are less costly where the full cobalt content is not needed. M48 has a density of 8.15 g/cm³ (0.294 lb/in³), heavier than 97% of steel grades. It melts at 1,250°C (2,282 °F). M48 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 10% and the elastic modulus is 225 GPa (32.6 Msi).
What is M48 used for?
- Heavy-duty milling cutters
- Broaches for hard/heat-resistant alloys
- High-performance drills and taps
- Cutting tools for superalloys
Advantages
- High service temperature — 500°C (932 °F), better than 90% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High strength — 620 MPa (89.9 ksi), better than 78% of steel grades
Limitations
- Low fracture toughness — 25 MPa·√m (22.8 ksi·√in), worse than 97% of steel grades
- High embodied carbon — 5.5 kg CO₂/kg, worse than 97% of steel grades
- Difficult to weld — 12/100, worse than 96% of steel grades
- Low electrical conductivity — 2.9 % IACS, worse than 93% of steel grades
- Difficult to machine — 25/100, worse than 93% of steel grades
M48 properties
Typical room-temperature values for M48-ANN; bars are the position among steel grades.
Physical3
M48 has a density of 8.15 g/cm³ (0.294 lb/in³), heavier than 97% of steel grades. It melts at 1,250°C (2,282 °F).
Mechanical15
M48 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 10% and the elastic modulus is 225 GPa (32.6 Msi).
Thermal6
M48 is rated for continuous service to 500°C (932 °F). It conducts heat at 23 W/m·K (13.3 BTU/hr·ft·°F), worse than 92% of steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
M48 conducts electricity at 2.9 % IACS, worse than 93% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of M48 takes about 60 MJ of energy and emits 5.5 kg of CO₂ — more than 96% of steel grades. Typical recycled content is 35%.
Manufacturability8
M48's machinability is poor (25/100, worse than 93% of steel grades); weldability not recommended (12/100); formability poor (20/100).
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. M48 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with M48
Is M48 easy to machine?
Machine only in the annealed condition with rigid setups, sharp cobalt-HSS or coated carbide, low speeds and heavy coolant; after hardening only grinding (CBN/SG wheels) or EDM — beware grinding burn and cracks.
Can M48 be welded?
Essentially non-weldable structurally; repair only by TIG/laser with matched HSS filler, 500-550 °C preheat and immediate multiple tempers.
Can M48 be formed, bent or molded?
Hot forge 1100-1150 °C, finish above 950 °C, slow cool then full spheroidize anneal (~870 °C, ≤20 °C/h to 600 °C); no cold forming.
M48 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 | 1.42 – 1.52 | 1.47 |
| Mn | 0.15 – 0.4 | 0.28 |
| Si | 0.15 – 0.4 | 0.28 |
| Cr | 3.5 – 4 | 3.75 |
| W | 9.5 – 10.5 | 10 |
| Mo | 4.75 – 5.5 | 5.1 |
| V | 2.75 – 3.25 | 3 |
| Co | 8 – 10 | 9 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on M48?
Finish by grinding/lapping; protect with black oxide, steam oxide, nitriding or PVD TiN/TiAlN — never anodize; oil or VCI wrap for storage.
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 M48 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- T11348
How much does M48 cost?
M48 is a high-cost steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
M48 — frequently asked
What is M48 used for?
M48 is typically used for heavy-duty milling cutters, broaches for hard/heat-resistant alloys, high-performance drills and taps and cutting tools for superalloys. In short: highest cobalt in family; exceptional red hardness; hardens to 68 HRC.
What is the yield strength of M48?
M48 has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is M48 easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Machine only in the annealed condition with rigid setups, sharp cobalt-HSS or coated carbide, low speeds and heavy coolant; after hardening only grinding (CBN/SG wheels) or EDM — beware grinding burn and cracks.
Can M48 be welded?
Not readily — weldability is rated not recommended (12/100). Essentially non-weldable structurally; repair only by TIG/laser with matched HSS filler, 500-550 °C preheat and immediate multiple tempers.
What surface finishes work on M48?
Finish by grinding/lapping; protect with black oxide, steam oxide, nitriding or PVD TiN/TiAlN — never anodize; oil or VCI wrap for storage.
Can M48 be formed, bent or molded?
Hot forge 1100-1150 °C, finish above 950 °C, slow cool then full spheroidize anneal (~870 °C, ≤20 °C/h to 600 °C); no cold forming.
What is the maximum service temperature of M48?
M48 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does M48 cost?
M48 is a high-cost steel ($$$$), 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 — Tool Steel High Speed Tool Steels — ASTM International (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (High-Speed Tool Steels) — ASM International (1990)
- ASM Specialty Handbook — Tool Materials — ASM International (1995)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
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.