Steel 25CrMoS4 +QT100 (+QT)
Heat-treated state
EN 25CrMoS4
Larger bar where reduced quench severity lowers the guaranteed strength class.
Values for the +QT100 condition
Other 25CrMoS4 tempers and conditions
25CrMoS4 is listed in 12 conditions; see the grade overview at 25CrMoS4.
Compare all 12 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose for cold heading, cold extrusion of fasteners or maximum drill/tap life before hardening. | 340 | 570 | 26 | 8 HRC | 8.3 % IACS |
Annealed | Lowest-hardness delivery condition for heavy machining, deep drilling or subsequent heat treatment. | 370 | 600 | 23 | 10 HRC | 8.2 % IACS |
Treated to ferrite-pearlite structure and hardness range | Specified when a defined, uniform F/P microstructure is needed for consistent automatic machining. | 390 | 630 | 21 | 12 HRC | 7.9 % IACS |
Normalized | Uniform fine ferrite-pearlite/bainite structure for forgings before machining or subsequent hardening. | 420 | 660 | 20 | 14 HRC | 8 % IACS |
Treated to hardness range | Ordered when only a hardness window (not full Q&T properties) is required for machining consistency. | 460 | 700 | 19 | 17 HRC | 7.8 % IACS |
+QT100This page +QT | Larger bar where reduced quench severity lowers the guaranteed strength class. | 500 | 780 | 17 | 21 HRC | 7.8 % IACS |
Cold drawn | Bright, close-tolerance bar for CNC turning where the part needs no further straightening. | 620 | 760 | 10 | 20 HRC | 7.9 % IACS |
+QTDefault Quenched and tempered | Standard stocked condition for shafts and machined parts needing ~800–950 MPa tensile with good toughness. | 650 | 880 | 16 | 27 HRC | — |
Quenched, tempered and cold drawn bright bar | Ready-to-machine bright bar combining Q&T strength with drawn tolerance/finish for hydraulic and fastener work. | 720 | 900 | 11 | 28 HRC | 7.5 % IACS |
+QT | Small-diameter bar/wire where full through-hardening gives the highest EN 10083-3 strength class. | 780 | 1,000 | 13 | 31 HRC | 7.5 % IACS |
Hardenability guaranteed | Order +H when the part is hardened by the user and the end-quench (Jominy) band must be guaranteed; delivered soft-annealed or normalized. | 1,150 | 1,450 | 9 | 45 HRC | 7.6 % IACS |
Restricted (narrowed) hardenability band, core-hardening quality | Pick +CH for high-volume automotive parts needing repeatable core hardness and low distortion from a narrowed Jominy scatter band. | 1,200 | 1,450 | 9 | 45 HRC | 7.6 % IACS |
What is 25CrMoS4 +QT100?
25CrMoS4 +QT100 is 25CrMoS4 heat treated to +QT100 — larger bar where reduced quench severity lowers the guaranteed strength class. 25CrMoS4 +QT100 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 63% of steel grades. Elongation at break is 17% and the elastic modulus is 210 GPa (30.5 Msi). 25CrMoS4 +QT100 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). +QT is the default condition FabDigit quotes; +QT100 is available on request or by drawing note.
Advantages
- Easy to machine — 67/100, better than 95% of steel grades
Limitations
- Hard to polish — 35/100, worse than 99% of steel grades
25CrMoS4 +QT100 properties
Typical room-temperature values for 25CrMoS4 +QT100; 23 are specific to this condition. Other listed values are 25CrMoS4 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
25CrMoS4 +QT100 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
25CrMoS4 +QT100 has a yield strength of 500 MPa (72.5 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 63% of steel grades. Elongation at break is 17% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
25CrMoS4 +QT100 is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
25CrMoS4 +QT100 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 25CrMoS4 +QT100 takes about 27 MJ of energy and emits 2.1 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 30%.
Manufacturability6
25CrMoS4 +QT100's machinability is good (67/100, better than 95% of steel grades); weldability poor (28/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 25CrMoS4 +QT100
Is 25CrMoS4 easy to machine?
Free-cutting behaviour is the point of this grade — MnS gives short chips and long tool life; best in +A/+AC (~78–80 % of AISI 1212), noticeably tougher when +QT above 280 HB.
Can 25CrMoS4 be welded?
Not recommended for structural welds: sulphur promotes hot cracking and CE ≈ 0.6 needs 200–300 °C preheat, low-hydrogen consumables and post-weld tempering.
Can 25CrMoS4 be formed, bent or molded?
Cold heading/upsetting only in the +AC spheroidized condition; hot forge 1050–850 °C then normalize, and expect anisotropy from sulphide stringers in transverse bends.
What surface finishes work on 25CrMoS4?
No corrosion resistance — protect by phosphate+oil, zinc or Zn-Ni plating (bake to avoid H embrittlement above 1000 MPa), QPQ nitrocarburising or paint; mirror polishing is limited by sulphide pitting.
25CrMoS4 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 |
| P | ≤ 0.03 | 0.02 |
| Sdeliberate sulphur addition for free machining | 0.02 – 0.04 | 0.03 |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.3 | 0.22 |
| Fe | balance | — |
25CrMoS4 +QT100 — frequently asked
What is 25CrMoS4 +QT100 used for?
25CrMoS4 +QT100 is typically used for bolts, shafts and precision machined parts. In short: free-machining Cr-Mo steel; best-machining 25CrMo4 variant; not for structural welds.
What is the yield strength of 25CrMoS4 +QT100?
25CrMoS4 +QT100 has a typical yield strength of 500 MPa (72.5 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 63% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is 25CrMoS4 +QT100 easy to machine?
Reasonably — machinability is rated good (67/100, better than 95% of steel grades). Free-cutting behaviour is the point of this grade — MnS gives short chips and long tool life; best in +A/+AC (~78–80 % of AISI 1212), noticeably tougher when +QT above 280 HB.
Can 25CrMoS4 +QT100 be welded?
Not readily — weldability is rated poor (28/100). Not recommended for structural welds: sulphur promotes hot cracking and CE ≈ 0.6 needs 200–300 °C preheat, low-hydrogen consumables and post-weld tempering.
What surface finishes work on 25CrMoS4 +QT100?
No corrosion resistance — protect by phosphate+oil, zinc or Zn-Ni plating (bake to avoid H embrittlement above 1000 MPa), QPQ nitrocarburising or paint; mirror polishing is limited by sulphide pitting.
Can 25CrMoS4 +QT100 be formed, bent or molded?
Cold heading/upsetting only in the +AC spheroidized condition; hot forge 1050–850 °C then normalize, and expect anisotropy from sulphide stringers in transverse bends.
What is the maximum service temperature of 25CrMoS4 +QT100?
25CrMoS4 +QT100 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.
Sources
- EN 10083-3 Steels for quenching and tempering — Alloy steels — CEN (2006)
- EN 10084 Case hardening steels (hardenability designations +H/+HH/+HL) — CEN (2008)
- EN 10277 Bright steel products — technical delivery conditions — CEN (2018)
- ASM Handbook Vol.1: Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19: Fatigue and Fracture — ASM International (1996)
- Cr-Mo engineering steel 1.7218/1.7213 data sheet — Böhler / Deutsche Edelstahlwerke (2020)
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.