Steel M48-HT65
Heat-treated state
AISI/SAE M48 · UNS T11348
HT65 = hardened & triple tempered
Pick when some edge toughness is needed (interrupted cuts, larger cutters) at slightly reduced red hardness.
Values for the HT65 condition
Other M48 tempers and conditions
M48 is listed in 3 conditions; see the grade overview at M48.
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 | — |
HT65This page Hardened & triple tempered | Pick when some edge toughness is needed (interrupted cuts, larger cutters) at slightly reduced red hardness. | — | 2,300 | 0 | 66 HRC | — |
What is M48-HT65?
M48-HT65 is M48 heat treated to HT65 — pick when some edge toughness is needed (interrupted cuts, larger cutters) at slightly reduced red hardness. M48-HT65 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 78% of steel grades. Elongation at break is 0% and the elastic modulus is 225 GPa (32.6 Msi). M48-HT65 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). ANN is the default condition FabDigit quotes; HT65 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 — 70/100, better than 87% of steel grades
- High strength — 620 MPa (89.9 ksi), better than 78% of steel grades
Limitations
- Limited ductility — 0%, worse than 100% of steel grades
- Difficult to machine — 5/100, worse than 100% of steel grades
- Limited formability — 2/100, worse than 100% of steel grades
- Low fracture toughness — 16 MPa·√m (14.6 ksi·√in), worse than 99% of steel grades
- Difficult to weld — 8/100, worse than 99% of steel grades
M48-HT65 properties
Typical room-temperature values for M48-HT65; 17 are specific to this condition. Other listed values are M48 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
M48-HT65 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-HT65 has a yield strength of 620 MPa (89.9 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 78% of steel grades. Elongation at break is 0% and the elastic modulus is 225 GPa (32.6 Msi).
Thermal6
M48-HT65 is rated for continuous service to 600°C (1,112 °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-HT65 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-HT65 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-HT65's machinability is not recommended (5/100, worse than 100% of steel grades); weldability not recommended (8/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with M48-HT65
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.
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.
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 | — |
M48-HT65 — frequently asked
What is M48-HT65 used for?
M48-HT65 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-HT65?
M48-HT65 has a typical yield strength of 620 MPa (89.9 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 78% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is M48-HT65 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, 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-HT65 be welded?
Not readily — weldability is rated not recommended (8/100). 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-HT65?
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-HT65 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-HT65?
M48-HT65 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.