Steel 25CrMo4 · heat-treated state
Steel 25CrMo4 +AC
Properties of the +AC condition, compared with the other 25CrMo4 tempers.
Spheroidize-annealed structure with globular carbides in ferrite — the softest and most cold-formable condition, used for cold heading and cold extrusion.
What is 25CrMo4 +AC?
25CrMo4 +AC is 25CrMo4 heat treated to +AC — spheroidize-annealed structure with globular carbides in ferrite — the softest and most cold-formable condition, used for cold heading and cold extrusion. 25CrMo4 +AC has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 78% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi). 25CrMo4 +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). Q&T 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
- Easy to machine — 62/100, better than 89% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
Limitations
- Low strength — 330 MPa (47.9 ksi), worse than 78% of steel grades
25CrMo4 +AC properties
Typical room-temperature values for 25CrMo4 +AC — 32 properties are specific to this condition; the rest are grade-level values shared by every 25CrMo4 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
25CrMo4 +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).
Mechanical16
25CrMo4 +AC has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 78% of steel grades. Elongation at break is 26% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
25CrMo4 +AC is rated for continuous service to 400°C (752 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
25CrMo4 +AC conducts electricity at 7.8 % IACS, worse than 58% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of 25CrMo4 +AC takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 55% of steel grades. Typical recycled content is 30%.
Manufacturability6
25CrMo4 +AC's machinability is good (62/100, better than 89% of steel grades); weldability good (55/100); formability very good (75/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 25CrMo4 tempers and conditions
25CrMo4 is also supplied in 10 other conditions. The full side-by-side table is on the 25CrMo4 overview.
- Q&TDefaultDefault stocked condition: balanced 800–950 MPa strength with good toughness for shafts, gears and pressure parts.650 MPa yield · 28 HRC
- +CHThrough-quenched and low-temperature tempered condition giving a hard martensitic core (~30–36 HRC) with restricted core hardenability band.900 MPa yield · 34 HRC
- Q&T 28-32 HRCPick when drawings call out a hardness band (shafts, sprockets, sour-service-adjacent pressure parts limited to ≤ 32 HRC).800 MPa yield · 30 HRC
- Q&T ≤16Pick for small shafts, bolts and thin tube where the full 900–1100 MPa strength class of EN 10083-3 is required.780 MPa yield · 31 HRC
- +CPick for close-tolerance bright bar with raised yield and good chip control when no post-machining heat treatment is planned.620 MPa yield · 235 HB
- Q&T 40-100Pick for heavier forgings/bars where limited hardenability lowers the guaranteed strength class to 700–850 MPa.520 MPa yield · 23 HRC
- +NPick for uniform fine-grained structure at moderate strength, typical for weldments and tube that will not be re-quenched.460 MPa yield · 215 HB
- +HGrade variant supplied with a guaranteed end-quench hardenability band (J1.5 ≈ 44–49 HRC); bar is normally delivered soft-annealed or normalized before the customer's own hardening.430 MPa yield · 200 HB
- +APick for maximum machinability and cold forming before the part is heat treated.400 MPa yield · 200 HB
- +SSoft delivery condition heat treated to a low, uniform hardness so that bar can be cold sheared into billets without cracking.380 MPa yield · 185 HB
- +ACSpheroidize-annealed structure with globular carbides in ferrite — the softest and most cold-formable condition, used for cold heading and cold extrusion.330 MPa yield · 170 HB
Working with 25CrMo4 +AC
Is 25CrMo4 easy to machine?
Machines like 4130: carbide at 100–160 m/min in Q&T state, rigid setups and positive rake; annealed bar cuts about 70 % of 1212.
Can 25CrMo4 be welded?
Good weldability with low-hydrogen filler (ER80S-D2 / E8018-B2); preheat 150–250 °C on sections above ~10 mm and stress-relieve or re-normalize thick weldments.
Can 25CrMo4 be formed, bent or molded?
Cold bend and roll in +A/+N condition only (generous radii); hot work 850–1100 °C then normalize or re-quench and temper.
What surface finishes work on 25CrMo4?
No inherent corrosion protection — phosphate + paint, zinc or Ni/Cd plating usual; bake after plating to avoid hydrogen embrittlement above ~1000 MPa; polishes to a bright finish.
25CrMo4 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 | 0.22 – 0.29 | 0.25 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.3 | 0.22 |
| P0.035 max for some product forms | ≤ 0.03 | — |
| S+S variant 0.020–0.040 for machinability | ≤ 0.04 | — |
| Fe | balance | — |
25CrMo4 +AC — frequently asked
What is 25CrMo4 +AC used for?
25CrMo4 +AC is typically used for bolts and high-tensile fasteners, industrial drive shafts, welded tubular frames and structures, hydraulic cylinder components, gear and sprocket blanks and pressure-retaining machined fittings. In short: premium Cr-Mo bar.
What is the yield strength of 25CrMo4 +AC?
25CrMo4 +AC has a typical yield strength of 330 MPa (47.9 ksi) and a tensile strength of 550 MPa (79.8 ksi) — weaker than 78% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 25CrMo4 +AC easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machines like 4130: carbide at 100–160 m/min in Q&T state, rigid setups and positive rake; annealed bar cuts about 70 % of 1212.
Can 25CrMo4 +AC be welded?
Yes — weldability is rated good (55/100). Good weldability with low-hydrogen filler (ER80S-D2 / E8018-B2); preheat 150–250 °C on sections above ~10 mm and stress-relieve or re-normalize thick weldments.
What surface finishes work on 25CrMo4 +AC?
No inherent corrosion protection — phosphate + paint, zinc or Ni/Cd plating usual; bake after plating to avoid hydrogen embrittlement above ~1000 MPa; polishes to a bright finish.
Can 25CrMo4 +AC be formed, bent or molded?
Cold bend and roll in +A/+N condition only (generous radii); hot work 850–1100 °C then normalize or re-quench and temper.
What is the maximum service temperature of 25CrMo4 +AC?
25CrMo4 +AC 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.
Can FabDigit make parts in 25CrMo4 +AC?
Yes — 25CrMo4 +AC 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
- EN 10083-3 Steels for quenching and tempering — alloy steels — CEN (2006)
- EN 10297-1 / EN 10305-1 seamless steel tubes (25CrMo4) — CEN (2016)
- GB/T 3077 (25CrMo) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- MMPDS-15 (AISI 4130 mechanical property tables) — Battelle/FAA (2020)
- 1.7218 / 25CrMo4 alloy steel datasheet — Böhler / Ovako (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.