Steel 18CrMoS4
EN 18CrMoS4
18CrMoS4 (1.7244) is the resulfurized free-machining version of 18CrMo4, a low-carbon Cr-Mo case-hardening steel to EN 10084.
Reference datasheet — 18CrMoS4 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 +AC condition
18CrMoS4 tempers and conditions
18CrMoS4 is supplied in 9 conditions, soft to hard. +AC is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ACDefault Spheroidize annealed | Standard stock condition: softest, most uniform microstructure for high-speed automatic machining and cold forming before carburizing. | 330 | 520 | 22 | 160 HB | — |
Peeled/turned and ground bright bar | Choose for defect-free, decarb-free surface and h9/h11 tolerance when the outer diameter is left as delivered. | 340 | 540 | 21 | 170 HB | 7.5 % IACS |
Annealed | General soft-annealed bar for rough machining before carburizing; hardness capped for consistent cutting. | 360 | 560 | 20 | 175 HB | — |
Treated for shearability | For coil/bar that will be cold-sheared into slugs for forging or cold heading without cracking. | 360 | 560 | 20 | 180 HB | 7.5 % IACS |
Normalized | Normalized bar/forging stock giving a uniform fine ferrite-pearlite structure and predictable distortion in later carburizing. | 400 | 620 | 18 | 11 HRC | 7.4 % IACS |
Treated to a specified hardness range | Pick when machine shops need a guaranteed narrow hardness band for unattended CNC/automatic turning. | 410 | 620 | 16 | 175 HB | 7.5 % IACS |
Spheroidize annealed then cold drawn | Bright cold-drawn bar: tight tolerance, smooth surface and higher strength for screw-machine parts fed from bar stock. | 530 | 660 | 9 | 200 HB | — |
Restricted hardenability (Jominy band), properties in blank-hardened… | Specify when case depth and core strength must be reproducible batch to batch; mechanicals quoted are for the blank-hardened (direct quench + low temper) test condition. | 740 | 1,030 | 10 | 33 HRC | — |
Carburized and hardened | Final service condition for gears, shafts and injector parts: hard wear-resistant case over a tough, moderately strong core. | 800 | 1,100 | 9 | 60 HRC | — |
What is 18CrMoS4?
18CrMoS4 (1.7244) is the resulfurized free-machining version of 18CrMo4, a low-carbon Cr-Mo case-hardening steel to EN 10084. The manganese sulfide inclusions break chips and extend tool life, which is why it is specified for high-volume turning on automatics before carburizing and hardening; bar and cold-drawn bar are the usual forms. Core properties in the delivered condition are about 330 MPa yield, 520 MPa tensile, 22 % elongation and 160 HB, with service to roughly 350 °C. The sulfur cuts transverse ductility and weldability (score 30), so choose sulfur-free 18CrMo4 where welding or high transverse toughness is required. 18CrMoS4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). 18CrMoS4 has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 78% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
What is 18CrMoS4 used for?
- mass-produced gears
- shafts machined on automatic lathes
- carburized transmission parts
- camshaft followers
Advantages
- Easy to machine — 65/100, better than 93% of steel grades
Limitations
- Hard to polish — 45/100, worse than 84% of steel grades
- Low strength — 330 MPa (47.9 ksi), worse than 78% of steel grades
18CrMoS4 properties
Typical room-temperature values for 18CrMoS4-+AC; bars are the position among steel grades.
Physical3
18CrMoS4 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
18CrMoS4 has a yield strength of 330 MPa (47.9 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 78% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
18CrMoS4 is rated for continuous service to 350°C (662 °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).
Electrical3
18CrMoS4 conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 18CrMoS4 takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability8
18CrMoS4's machinability is good (65/100, better than 93% of steel grades); weldability poor (30/100); formability good (60/100).
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. 18CrMoS4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 18CrMoS4
Is 18CrMoS4 easy to machine?
Excellent for automatics in +AC/+AC+C: MnS gives short chips; run carbide at 150–220 m/min, avoid re-annealing after final turning to keep dimensions.
Can 18CrMoS4 be welded?
Poor — sulfur promotes hot cracking and Cr-Mo hardens the HAZ; if unavoidable use low-hydrogen consumables, 200–300 °C preheat and immediate stress relief.
Can 18CrMoS4 be formed, bent or molded?
Spheroidized condition takes moderate cold heading/extrusion; cold-drawn bar has little remaining ductility, so bend generously or normalize first.
18CrMoS4 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 | 0.15 – 0.21 | 0.18 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | 0.02 |
| Sdeliberate resulfurization for machinability | 0.02 – 0.04 | 0.03 |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.25 | 0.2 |
| Fe | balance |
What surface finishes work on 18CrMoS4?
Not anodizable; protect with zinc or manganese phosphate, black oxide, Zn-Ni plating or oil; grind case-hardened surfaces to remove distortion and any decarb.
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 18CrMoS4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 18CrMoS4 cost?
18CrMoS4 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.
18CrMoS4 — frequently asked
What is 18CrMoS4 used for?
18CrMoS4 is typically used for mass-produced gears, shafts machined on automatic lathes, carburized transmission parts and camshaft followers. In short: free-machining 18CrMo4; built for automatic lathes; reduced transverse ductility.
What is the yield strength of 18CrMoS4?
18CrMoS4 has a typical yield strength of 330 MPa (47.9 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 78% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 18CrMoS4 easy to machine?
Reasonably — machinability is rated good (65/100, better than 93% of steel grades). Excellent for automatics in +AC/+AC+C: MnS gives short chips; run carbide at 150–220 m/min, avoid re-annealing after final turning to keep dimensions.
Can 18CrMoS4 be welded?
Not readily — weldability is rated poor (30/100). Poor — sulfur promotes hot cracking and Cr-Mo hardens the HAZ; if unavoidable use low-hydrogen consumables, 200–300 °C preheat and immediate stress relief.
What surface finishes work on 18CrMoS4?
Not anodizable; protect with zinc or manganese phosphate, black oxide, Zn-Ni plating or oil; grind case-hardened surfaces to remove distortion and any decarb.
Can 18CrMoS4 be formed, bent or molded?
Spheroidized condition takes moderate cold heading/extrusion; cold-drawn bar has little remaining ductility, so bend generously or normalize first.
What is the maximum service temperature of 18CrMoS4?
18CrMoS4 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.
What is the difference between 18CrMoS4 +AC and 18CrMoS4-CH?
+AC is the default condition — standard stock condition: softest, most uniform microstructure for high-speed automatic machining and cold forming before carburizing. CH: final service condition for gears, shafts and injector parts: hard wear-resistant case over a tough, moderately strong core. Yield strength is 330 MPa in +AC versus 800 MPa in CH.
How much does 18CrMoS4 cost?
18CrMoS4 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
- EN 10084 — Case hardening steels: technical delivery conditions — 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. 4A/4D — Heat Treating (carburizing of Cr-Mo case-hardening steels) — ASM International (2014)
- Case-hardening steel 18CrMo4 / 18CrMoS4 (1.7243 / 1.7244) datasheet — European long-products mills (e.g. Ovako / Deutsche Edelstahlwerke) (2022)
- SAE J404 / AISI 4118 chemical composition — SAE International (2021)
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.