Steel 18CrMo4
EN 18CrMo4
A low-carbon chromium-molybdenum case-hardening steel offering good core toughness and a hard, wear-resistant carburized surface; used where moderate strength gears and shafts need through-hardenable, weldable cores.
Reference datasheet — 18CrMo4 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
18CrMo4 tempers and conditions
18CrMo4 is supplied in 6 conditions, soft to hard. +AC is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
+ACDefault Spheroidize annealed | Standard as-supplied bar and wire state: spheroidize annealing gives the lowest hardness and best machining and cold forming before the user carburizes and quenches. | 350 | 570 | 22 | 170 HB | — |
Normalized | Common delivery state for forgings and hot-rolled bar: normalizing gives a uniform structure and slightly higher strength than annealed while easing later carburizing. | 420 | 640 | 19 | 12 HRC | 7.7 % IACS |
Spheroidize annealed and cold drawn | Pick bright cold-drawn bar for close size tolerance and good surface on automatic-lathe parts and later carburizing; work hardening lifts strength to 700 MPa but drops elongation to 10%. | 550 | 700 | 10 | 210 HB | — |
Hardenability-guaranteed (Jominy band), carburized and hardened core… | Order with the guaranteed Jominy hardenability band for gears and shafts: carburizing, quenching and low tempering give a 58–62 HRC case over a strong, tough core. | 680 | 950 | 11 | 30 HRC | — |
Carburized + hardened + low tempered | Final state of finished gears and shafts: carburized, hardened and low tempered to a 0.5–1.5 mm wear-resistant case over a tough core, so allow stock for grinding. | 700 | 1,000 | 9 | 60 HRC | — |
Quenched and tempered | Choose quenched and tempered when the part runs through-hardened instead of carburized: moderate strength with good toughness for small and medium shafts and fasteners. | 780 | 1,000 | 12 | 33 HRC | — |
What is 18CrMo4?
A low-carbon chromium-molybdenum case-hardening steel offering good core toughness and a hard, wear-resistant carburized surface; used where moderate strength gears and shafts need through-hardenable, weldable cores. 18CrMo4 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). 18CrMo4 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 74% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
What is 18CrMo4 used for?
- gears
- shafts
- case-hardened pins
- camshafts
- chain components
Advantages
- Forms and bends easily — 70/100, better than 86% of steel grades
18CrMo4 properties
Typical room-temperature values for 18CrMo4-+AC; bars are the position among steel grades.
Physical3
18CrMo4 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
18CrMo4 has a yield strength of 350 MPa (50.8 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 74% of steel grades. Elongation at break is 22% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
18CrMo4 is rated for continuous service to 400°C (752 °F). It conducts heat at 43 W/m·K (24.8 BTU/hr·ft·°F), better than 51% of steel grades. Thermal expansion is 11.6 µm/m·K (6.44 µin/in·°F).
Electrical3
18CrMo4 conducts electricity at 7.7 % IACS, worse than 65% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 18CrMo4 takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
18CrMo4's machinability is good (60/100, better than 83% of steel grades); weldability good (68/100); formability very good (70/100).
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. 18CrMo4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 18CrMo4
Is 18CrMo4 easy to machine?
Machining is best in the spheroidize-annealed or cold-drawn condition, with coated carbide at 120–180 m/min. Once carburized and quenched, only grinding or hard turning with CBN is practical.
Can 18CrMo4 be welded?
Carbon equivalent is about 0.55, so the steel is weldable with 150–250 °C preheat and low-hydrogen consumables, followed by stress relief at 550–650 °C. Do not weld on carburized surfaces.
Can 18CrMo4 be formed, bent or molded?
The +AC condition suits cold heading, cold extrusion and thread rolling. Hot forge at 1100–850 °C and normalize after forging to refine the structure.
18CrMo4 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 | |
| SLow/controlled-sulfur grades also specify S 0.020-0.040 | ≤ 0.04 | |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.25 | 0.2 |
| Fe | balance |
What surface finishes work on 18CrMo4?
Corrosion protection is required: black oxide, phosphating, zinc or nickel plating, or paint. Carburized gear teeth are ground after hardening and can be shot peened to improve 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 18CrMo4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 18CrMo4 cost?
18CrMo4 is a budget-cost steel ($), cheaper than about 90% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
18CrMo4 — frequently asked
What is 18CrMo4 used for?
18CrMo4 is typically used for gears, shafts, case-hardened pins, camshafts and chain components. In short: weldable case-hardening steel; tough core, 58–62 HRC case; direct 4118/SCM418 equivalent.
What is the yield strength of 18CrMo4?
18CrMo4 has a typical yield strength of 350 MPa (50.8 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 74% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is 18CrMo4 easy to machine?
Reasonably — machinability is rated good (60/100, better than 83% of steel grades). Machining is best in the spheroidize-annealed or cold-drawn condition, with coated carbide at 120–180 m/min. Once carburized and quenched, only grinding or hard turning with CBN is practical.
Can 18CrMo4 be welded?
Yes — weldability is rated good (68/100). Carbon equivalent is about 0.55, so the steel is weldable with 150–250 °C preheat and low-hydrogen consumables, followed by stress relief at 550–650 °C. Do not weld on carburized surfaces.
What surface finishes work on 18CrMo4?
Corrosion protection is required: black oxide, phosphating, zinc or nickel plating, or paint. Carburized gear teeth are ground after hardening and can be shot peened to improve fatigue life.
Can 18CrMo4 be formed, bent or molded?
The +AC condition suits cold heading, cold extrusion and thread rolling. Hot forge at 1100–850 °C and normalize after forging to refine the structure.
What is the maximum service temperature of 18CrMo4?
18CrMo4 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does 18CrMo4 cost?
18CrMo4 is a budget-cost steel ($), 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)
- GB/T 3077 (20CrMo ) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- Machinery's Handbook (machinability ratings) — Industrial Press (2020)
- Case hardening steel 18CrMo4 / 1.7243 data sheet — European long-products producers (2022)
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.