Steel 70Mn4
EN 70Mn4 · GB 70Mn
70Mn4 (1.1244, 70Mn) is a high-carbon manganese steel with about 0.70 % C and roughly 1 % Mn, giving greater hardenability than plain 70-carbon grades for spring and wear applications.
Reference datasheet — 70Mn4 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 +A condition
70Mn4 tempers and conditions
70Mn4 is supplied in 8 conditions, soft to hard. +A is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ADefault Annealed | Softest supply condition — pick for machining, deep blanking/forming or cold drawing before hardening. | 400 | 650 | 15 | 205 HB | 47 W/m·K |
Treated for improved shearability | Controlled lamellar/partly spheroidised structure with a capped hardness band — pick when bars or strip are cold-sheared, cropped or blanked to slug/blank with clean cut faces. | 480 | 800 | 10 | 24 HRC | — |
Normalized | Uniform fine pearlitic structure — pick to reset grain size after hot forming and before hardening. | 520 | 900 | 9 | 26 HRC | — |
Hot rolled | Cheapest supply form — pick when the part will be fully re-heat-treated anyway. | 550 | 950 | 8 | 29 HRC | 9 % IACS |
Cold drawn | Work-hardened strip or patented drawn wire — pick for flat springs, shims and clips used without further hardening. | 1,000 | 1,150 | 3 | 36 HRC | — |
+QT 40–45 HRC | Tempered around 450–500 °C — pick for tough, high-strength wear parts where some ductility is still needed. | 1,200 | 1,400 | 8 | 42 HRC | 44 W/m·K |
+QT 48–52 HRC | Classic oil-hardened-and-tempered spring/blade condition — pick for flat springs, retaining rings and cutting blades. | 1,550 | 1,750 | 5 | 50 HRC | 43 W/m·K |
Hardened | Maximum surface hardness for wear and rolling contact — pick for induction-hardened tracks, pins and wear plates; brittle and must not be shock-loaded. | 1,800 | 2,100 | 1 | 60 HRC | 42 W/m·K |
What is 70Mn4?
70Mn4 (1.1244, 70Mn) is a high-carbon manganese steel with about 0.70 % C and roughly 1 % Mn, giving greater hardenability than plain 70-carbon grades for spring and wear applications. Annealed bar and strip run 400 MPa yield, 650 MPa tensile, 15 % elongation and 205 HB, with +QT40, +QT48 and +H58 conditions available for hardened service to 400 °C. It is used for induction-hardened bearing components, springs, wear plates and cutting tools. Weldability is effectively nil (score 15, CE ≈ 0.9), formability is limited to annealed strip and corrosion resistance is zero (score 10); 56Mn4 is the lower-carbon alternative. 70Mn4 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). 70Mn4 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 650 MPa (94.3 ksi) — weaker than 60% of steel grades. Elongation at break is 15% and the elastic modulus is 207 GPa (30 Msi).
What is 70Mn4 used for?
- Induction-hardened bearing components
- Springs
- Wear plates
- Cutting tools
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to weld — 15/100, worse than 91% of steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
70Mn4 properties
Typical room-temperature values for 70Mn4-+A; bars are the position among steel grades.
Physical3
70Mn4 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).
Mechanical16
70Mn4 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 650 MPa (94.3 ksi) — weaker than 60% of steel grades. Elongation at break is 15% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
70Mn4 is rated for continuous service to 400°C (752 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), better than 75% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
70Mn4 conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 70Mn4 takes about 26 MJ of energy and emits 2.1 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 25%.
Manufacturability7
70Mn4's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (15/100); formability fair (45/100).
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. 70Mn4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 70Mn4
Is 70Mn4 easy to machine?
Machine only in the +A or +S condition with sharp carbide tooling and generous coolant; above ~45 HRC switch to grinding, CBN turning or EDM.
Can 70Mn4 be welded?
Effectively non-weldable for structural joints (CE ≈ 0.9); if unavoidable, preheat 250–350 °C, use low-hydrogen consumables and post-weld temper immediately.
Can 70Mn4 be formed, bent or molded?
Bend and blank only from the annealed strip with bend radii ≥ 2–3 t across the rolling direction; hot form 850–1050 °C, then normalize before hardening — harden 800–830 °C in oil, temper 160–500 °C to the required hardness.
70Mn4 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 |
|---|---|---|
| Cgrade-defining carbon level | 0.65 – 0.75 | 0.7 |
| Si | 0.15 – 0.35 | 0.25 |
| Mnraises hardenability vs plain C70 | 0.9 – 1.2 | 1 |
| Pimpurity limit | ≤ 0.03 | |
| Simpurity limit | ≤ 0.03 | |
| Crresidual | ≤ 0.4 | |
| Niresidual | ≤ 0.4 | |
| Curesidual | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on 70Mn4?
No inherent corrosion protection — phosphate + oil, black oxide, zinc or Zn-Ni plating (bake 190 °C ≥ 4 h after plating to avoid hydrogen embrittlement); shot peening markedly improves 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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 70Mn4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- EN / DIN / Werkstoff-Nr.
- 1.1244
- GB (China)
- 70Mn
How much does 70Mn4 cost?
70Mn4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
70Mn4 — frequently asked
What is 70Mn4 used for?
70Mn4 is typically used for induction-hardened bearing components, springs, wear plates and cutting tools. In short: hardenable spring and wear steel; higher carbon than 56Mn4; essentially non-weldable.
What is the yield strength of 70Mn4?
70Mn4 has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 650 MPa (94.3 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is 70Mn4 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine only in the +A or +S condition with sharp carbide tooling and generous coolant; above ~45 HRC switch to grinding, CBN turning or EDM.
Can 70Mn4 be welded?
Not readily — weldability is rated poor (15/100). Effectively non-weldable for structural joints (CE ≈ 0.9); if unavoidable, preheat 250–350 °C, use low-hydrogen consumables and post-weld temper immediately.
What surface finishes work on 70Mn4?
No inherent corrosion protection — phosphate + oil, black oxide, zinc or Zn-Ni plating (bake 190 °C ≥ 4 h after plating to avoid hydrogen embrittlement); shot peening markedly improves spring fatigue life.
Can 70Mn4 be formed, bent or molded?
Bend and blank only from the annealed strip with bend radii ≥ 2–3 t across the rolling direction; hot form 850–1050 °C, then normalize before hardening — harden 800–830 °C in oil, temper 160–500 °C to the required hardness.
What is the maximum service temperature of 70Mn4?
70Mn4 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 70Mn4 cost?
70Mn4 is a budget-cost steel ($), 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
- DIN 17222 — Cold rolled steel strip for springs — DIN (1979)
- EN 10132-4 — Cold rolled narrow steel strip for heat treatment: spring steels — CEN (2000)
- EN 10083-2 — Steels for quenching and tempering: non-alloy steels (delivery conditions +A, +S, +N, +QT) — CEN (2006)
- Stahlschlüssel / Key to Steel — material No. 1.1244 (70Mn4) — Verlag Stahlschlüssel Wegst (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook (machinability ratings, heat-treat practice) — Industrial Press (2020)
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.