Steel 65Mn
GB 65Mn · AISI/SAE 1566
65Mn is a carbon–manganese spring steel (AISI 1566 equivalent) that gets its hardenability from about 0.65 % carbon plus manganese rather than from alloy additions.
Values for the Annealed condition
65Mn tempers and conditions
65Mn is supplied in 6 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault Annealed (spheroidise / soft annealed, mill delivery) | Default stocked condition — softest state for machining, blanking and cold forming before hardening. | 440 | 760 | 16 | 215 HB | — |
Hot Rolled (as-rolled bar / plate) | Cheapest mill condition for stock that will be re-heat-treated by the fabricator. | 520 | 900 | 12 | 25 HRC | 8.5 % IACS |
Normalized (≈820–840 °C, air cooled) | Grain-refining pre-treatment for forgings and heavy bar before final quench and temper. | 560 | 930 | 12 | 26 HRC | 8.5 % IACS |
Cold Drawn / cold rolled hard (as-worked strip & wire) | Work-hardened strip or wire used where hardness is achieved without heat treatment (washers, shims, clips). | 900 | 1,050 | 6 | 31 HRC | 8.5 % IACS |
oil quench + low temper 350–420 °C (spring temper, 44–48 HRC) | Standard spring temper for leaf springs, saw blades and clutch plates — maximum elastic limit with usable toughness. | 1,400 | 1,600 | 5 | 46 HRC | — |
Hardened & Tempered, low temper 180–250 °C | Pick for wear-critical thin sections — blades, scrapers, mower and saw teeth — where edge retention beats toughness. | 1,650 | 1,950 | 2 | 53 HRC | — |
What is 65Mn?
65Mn is a carbon–manganese spring steel (AISI 1566 equivalent) that gets its hardenability from about 0.65 % carbon plus manganese rather than from alloy additions. It is chosen for small-to-medium springs, saw blades and clips, and is stocked as hot-rolled, normalized and cold-drawn bar, annealed strip and hardened-and-tempered material at 50–55 HRC. Default annealed values are 440 MPa yield, 760 MPa tensile, 16 % elongation and 215 HB, with service to about 350 °C. Weldability is poor and there is no bare corrosion resistance; for thicker sections needing deeper hardening, 5150 chromium spring steel is the usual step up. 65Mn has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). 65Mn has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 50% of steel grades. Elongation at break is 16% and the elastic modulus is 206 GPa (29.9 Msi).
What is 65Mn used for?
- Coil springs
- Saw blades
- Springs
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Difficult to weld — 25/100, worse than 77% of steel grades
65Mn properties
Typical room-temperature values for 65Mn-Annealed; bars are the position among steel grades.
Physical3
65Mn has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical14
65Mn has a yield strength of 440 MPa (63.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 50% of steel grades. Elongation at break is 16% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
65Mn is rated for continuous service to 350°C (662 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
65Mn conducts electricity at 8.5 % IACS, better than 63% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 65Mn takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
65Mn's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (25/100); formability fair (50/100).
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. 65Mn is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 65Mn
Is 65Mn easy to machine?
Machine only in the spheroidise-annealed state (≈55 % of 1212); hardened 65Mn needs grinding, CBN or carbide at low feed.
Can 65Mn be welded?
Poor — 0.66 % C gives hard, crack-prone HAZ; if unavoidable use preheat 250–350 °C, low-hydrogen filler and immediate stress-relief/temper, then re-heat-treat.
Can 65Mn be formed, bent or molded?
Blank and bend in the annealed condition with generous radii (≥3 t); hardened spring temper allows only light setting, so form first and heat-treat after; oil quench 810–840 °C, temper 350–420 °C for spring properties.
Manufacturability
The process limits FabDigit's quote engine applies to 65Mn. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Fair50 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Better50 / 100 |
|---|---|
| Weldability | Fair25 / 100 |
| Bendable | Yes |
65Mn 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 |
|---|---|---|
| CGB/T 1222 | 0.62 – 0.7 | 0.66 |
| Si | 0.17 – 0.37 | 0.27 |
| Mnraises hardenability vs 1065 | 0.9 – 1.2 | 1.05 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Crresidual max | ≤ 0.25 | |
| Niresidual max | ≤ 0.35 | |
| Curesidual max | ≤ 0.25 | |
| Fe | balance |
What surface finishes work on 65Mn?
No anodising — protect with oil, phosphate + oil, black oxide, zinc or Zn-Ni plating (bake to avoid hydrogen embrittlement above 40 HRC); grinds and polishes well when hardened; shot peening markedly raises spring fatigue life.
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
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 65Mn in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- AISI / SAE
- 1566
How much does 65Mn cost?
65Mn is a standard-cost steel ($$), cheaper than about 62% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
65Mn — frequently asked
What is 65Mn used for?
65Mn is typically used for coil springs, saw blades and springs. In short: medium-carbon spring bar.
What is the yield strength of 65Mn?
65Mn has a typical yield strength of 440 MPa (63.8 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 50% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 65Mn easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine only in the spheroidise-annealed state (≈55 % of 1212); hardened 65Mn needs grinding, CBN or carbide at low feed.
Can 65Mn be welded?
Not readily — weldability is rated poor (25/100). Poor — 0.66 % C gives hard, crack-prone HAZ; if unavoidable use preheat 250–350 °C, low-hydrogen filler and immediate stress-relief/temper, then re-heat-treat.
What surface finishes work on 65Mn?
No anodising — protect with oil, phosphate + oil, black oxide, zinc or Zn-Ni plating (bake to avoid hydrogen embrittlement above 40 HRC); grinds and polishes well when hardened; shot peening markedly raises spring fatigue life.
Can 65Mn be formed, bent or molded?
Blank and bend in the annealed condition with generous radii (≥3 t); hardened spring temper allows only light setting, so form first and heat-treat after; oil quench 810–840 °C, temper 350–420 °C for spring properties.
What is the maximum service temperature of 65Mn?
65Mn is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 65Mn cost?
65Mn is a standard-cost steel ($$), cheaper than about 62% 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 65Mn?
Yes — 65Mn is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- GB/T 1222 Spring steels (2016)
- GB/T 699 Quality carbon structural steels — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
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.