Steel 17MnCr5 +AC (Spheroidize annealed)
Heat-treated state
EN 17MnCr5 · AISI/SAE 5115
Softest condition — pick for cold heading, cold extrusion and deep cold forming of blanks before carburizing.
Values for the +AC condition
Other 17MnCr5 tempers and conditions
17MnCr5 is listed in 6 conditions; see the grade overview at 17MnCr5.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ACThis page Spheroidize annealed | Softest condition — pick for cold heading, cold extrusion and deep cold forming of blanks before carburizing. | 340 | 560 | 25 | 165 HB | 8.2 % IACS |
Annealed to a ferrite-pearlite structure with specified hardness range | Choose when consistent chip formation and dimensional stability in automatic machining are required. | 370 | 600 | 21 | 175 HB | 8.2 % IACS |
+ADefault Annealed | Standard stock condition for bar and tube: soft, easily machined before carburizing. | 380 | 620 | 20 | 180 HB | — |
Supplied with specified (standard) hardenability, Jominy-controlled | Order this when case and core hardness after carburizing must be reproducible batch to batch (Jominy band guaranteed). | 400 | 640 | 19 | 190 HB | 8.2 % IACS |
Treated to a specified hardness range | Bar supplied within a narrow hardness band so machining parameters and shear/cropping behaviour are repeatable. | 420 | 660 | 18 | 195 HB | 8.2 % IACS |
Carburized, quenched and low-temperature tempered | Final service condition of finished gears/bearing parts: hard wear-resistant case over a tough, strong core. | 700 | 1,000 | 10 | 60 HRC | — |
What is 17MnCr5 +AC?
17MnCr5 +AC is 17MnCr5 heat treated to +AC — softest condition — pick for cold heading, cold extrusion and deep cold forming of blanks before carburizing. 17MnCr5 +AC has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 76% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi). 17MnCr5 +AC 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). +A is the default condition FabDigit quotes; +AC is available on request or by drawing note.
Advantages
- Forms and bends easily — 75/100, better than 90% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Low strength — 340 MPa (49.3 ksi), worse than 76% of steel grades
17MnCr5 +AC properties
Typical room-temperature values for 17MnCr5 +AC; 23 are specific to this condition. Other listed values are 17MnCr5 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
17MnCr5 +AC 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
17MnCr5 +AC has a yield strength of 340 MPa (49.3 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 76% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
17MnCr5 +AC is rated for continuous service to 180°C (356 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical2
17MnCr5 +AC has an electrical resistivity of 2.1×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 17MnCr5 +AC takes about 32 MJ of energy and emits 2.2 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 30%.
Manufacturability7
17MnCr5 +AC's machinability is good (55/100, better than 62% of steel grades); weldability good (58/100); formability very good (75/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 17MnCr5 +AC
Is 17MnCr5 easy to machine?
Machine fully in the soft (+A/+FP/+TH) condition with carbide tooling and generous coolant, leaving 0.2–0.4 mm grinding stock for post-carburizing distortion.
Can 17MnCr5 be welded?
Weldable as low-carbon alloy steel before carburizing (preheat ~150 °C for heavy sections); do not weld carburized surfaces — hard case cracks.
Can 17MnCr5 be formed, bent or molded?
Good cold heading and extrusion in the spheroidized +AC condition; hot forge 1100–850 °C followed by controlled cooling or normalizing.
What surface finishes work on 17MnCr5?
Not anodizable; protect with oil, Mn/Zn phosphate, black oxide or zinc plating (bake to avoid hydrogen embrittlement), grind and hone bearing surfaces after carburizing.
17MnCr5 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 | 0.14 – 0.19 | 0.17 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 1 – 1.3 | 1.15 |
| P | ≤ 0.03 | — |
| Smax; low-S or controlled-S variants available | ≤ 0.04 | — |
| Cr | 0.8 – 1.1 | 0.95 |
| Fe | balance | — |
17MnCr5 +AC — frequently asked
What is 17MnCr5 +AC used for?
17MnCr5 +AC is typically used for carburized gears, bearing rollers and shafts. In short: case-hardening gear steel; AISI 5115 equivalent; good cold-heading grade.
What is the yield strength of 17MnCr5 +AC?
17MnCr5 +AC has a typical yield strength of 340 MPa (49.3 ksi) and a tensile strength of 560 MPa (81.2 ksi) — weaker than 76% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 17MnCr5 +AC easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machine fully in the soft (+A/+FP/+TH) condition with carbide tooling and generous coolant, leaving 0.2–0.4 mm grinding stock for post-carburizing distortion.
Can 17MnCr5 +AC be welded?
Yes — weldability is rated good (58/100). Weldable as low-carbon alloy steel before carburizing (preheat ~150 °C for heavy sections); do not weld carburized surfaces — hard case cracks.
What surface finishes work on 17MnCr5 +AC?
Not anodizable; protect with oil, Mn/Zn phosphate, black oxide or zinc plating (bake to avoid hydrogen embrittlement), grind and hone bearing surfaces after carburizing.
Can 17MnCr5 +AC be formed, bent or molded?
Good cold heading and extrusion in the spheroidized +AC condition; hot forge 1100–850 °C followed by controlled cooling or normalizing.
What is the maximum service temperature of 17MnCr5 +AC?
17MnCr5 +AC is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 17MnCr5 +A and 17MnCr5 CARB-QT?
+A is the default condition — standard stock condition for bar and tube: soft, easily machined before carburizing. CARB-QT: final service condition of finished gears/bearing parts: hard wear-resistant case over a tough, strong core. Yield strength is 380 MPa in +A versus 700 MPa in CARB-QT.
Sources
- EN 10084 — Case hardening steels: technical delivery conditions — CEN (2008)
- EN 10083-1 / EN 10250-3 general delivery and bar conditions — CEN (2006)
- SAE J404 — Chemical compositions of SAE alloy steels (5115) — SAE International (2009)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 4A — Steel Heat Treating Fundamentals (carburizing) — ASM International (2013)
- Case-hardening steel 1.3521 / 17MnCr5 data sheet — European long-products mill (typical values) (2022)
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.