Steel 42CrMo4
EN 42CrMo4 · AISI/SAE 4140 · JIS SCM440 · GB 42CrMo
42CrMo4 (1.7225) is the EN 10083 chromium-molybdenum quenched-and-tempered alloy steel, equivalent to AISI 4140, GB 42CrMo and JIS SCM440.
Values for the HR condition
42CrMo4 tempers and conditions
42CrMo4 is supplied in 17 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 17 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Annealed to globular (spheroidized) carbides for the softest, most ductile structure — the preferred feedstock for cold extrusion, cold heading and deep machining. | 380 | 630 | 24 | 185 HB | 44 W/m·K |
soft annealed (+A), max 241 HB | Softest condition — pick it for deep machining, cold forming or as a pre-heat-treat blank. | 415 | 655 | 20 | 13 HRC | — |
Treated for High Shearability | EN 10083 delivery condition treated to a controlled soft structure (≤248 HB) so that bar can be cold-sheared into billets without cracking. | 450 | 750 | 18 | 220 HB | 43 W/m·K |
Cold rolled | Thin strip/sheet form for stamped or formed blanks that are hardened afterwards. | 480 | 700 | 12 | 17 HRC | 7.8 % IACS |
HRDefault Hot rolled | Cheapest stock form for parts that will be heat treated after rough machining. | 550 | 850 | 14 | 23 HRC | — |
Q&T strength class Rm 750–900 MPa (bar 160–250 mm) | Lowest EN 10083-3 Q&T class, used for heavy sections where full hardening depth is impossible. | 560 | 820 | 16 | 23 HRC | 7.8 % IACS |
Q&T strength class Rm 800–950 MPa (bar 100–160 mm) | Medium-section Q&T class for large shafts and forged rings. | 610 | 880 | 15 | 26 HRC | 7.8 % IACS |
Cold drawn | Bright, close-tolerance bar for turned parts and shafting where no further heat treatment is planned. | 650 | 850 | 10 | 25 HRC | — |
air cooled from ~870 °C | Uniform fine-grain structure for forgings and weld fabrications before final quench and temper. | 650 | 1,000 | 18 | 30 HRC | — |
Q&T strength class Rm 900–1100 MPa (bar 40–100 mm) | Most common ordered Q&T class for medium-diameter shafts and gear blanks. | 720 | 1,000 | 14 | 31 HRC | 7.8 % IACS |
Carburized and hardened | Bar hardened and tempered to a specified core hardness band (typically ~280–320 HB), the usual pre-condition before nitriding or induction case hardening. | 800 | 1,000 | 13 | 31 HRC | 43 W/m·K |
Q&T strength class Rm 1000–1200 MPa (bar 16–40 mm) | Higher-strength class for small shafts, pins, high-tensile bolting and connecting rods. | 820 | 1,100 | 12 | 34 HRC | 7.8 % IACS |
Induction hardened | For journals, splines and gear teeth needing 50–58 HRC wear surface with a ductile core. | 830 | 1,000 | 12 | 54 HRC | 7.8 % IACS |
Quenched and tempered | Standard delivered condition for loaded shafts, gears and couplings; best strength/toughness balance. | 850 | 1,000 | 14 | 31 HRC | — |
Pre-hardened ("4140 HT") stock | Distributor pre-hardened bar/plate machined to final size with no further heat treatment; also the NACE-friendly upper bound is 22 HRC, so check sour-service specs. | 850 | 1,000 | 15 | 30 HRC | 7.8 % IACS |
Q&T core + gas/plasma nitrided case | Choose for wear surfaces and better fatigue/corrosion on shafts and dies; case is 0.2–0.5 mm deep with a tough Q&T core. | 850 | 1,000 | 13 | 31 HRC | 7.8 % IACS |
Q&T strength class Rm 1100–1300 MPa (bar ≤16 mm) | Maximum standard Q&T class; highest strength but lowest toughness and highest cracking sensitivity. | 980 | 1,200 | 10 | 38 HRC | 7.8 % IACS |
What is 42CrMo4?
42CrMo4 (1.7225) is the EN 10083 chromium-molybdenum quenched-and-tempered alloy steel, equivalent to AISI 4140, GB 42CrMo and JIS SCM440. It is chosen for high strength with useful toughness in medium sections and is stocked as hot-rolled, cold-drawn, annealed, normalized and Q&T bar, plate and forgings; the default Q&T condition gives 550 MPa yield, 850 MPa tensile, 14 % elongation and 245 HB (23 HRC), with QT700-QT1100 classes, 28-32 HRC, nitrided and induction-hardened options on file. Service is limited to roughly 400 °C, the steel has no inherent corrosion resistance, and welding needs preheat and post-weld temper. For heavier sections requiring deeper hardening, SNCM439 / 4340 is the next step up. 42CrMo4 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). 42CrMo4 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 71% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
What is 42CrMo4 used for?
- Drive shafts and axles
- Gears and pinions
- Forged industrial parts
- Hydraulic cylinder rods
- High-strength bolts and studs
- Crankshafts
- Spindles and couplings
- Die and mould holders
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Limited ductility — 14%, worse than 75% of steel grades
42CrMo4 properties
Typical room-temperature values for 42CrMo4-HR; bars are the position among steel grades.
Physical3
42CrMo4 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
42CrMo4 has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 71% of steel grades. Elongation at break is 14% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
42CrMo4 is rated for continuous service to 400°C (752 °F). It conducts heat at 42.6 W/m·K (24.6 BTU/hr·ft·°F), worse than 51% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
42CrMo4 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 42CrMo4 takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
42CrMo4's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (35/100); formability fair (35/100).
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. 42CrMo4 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 42CrMo4
Is 42CrMo4 easy to machine?
Machine annealed (≤241 HB) or at 28–32 HRC with rigid setups, coated carbide, 80–160 m/min and generous coolant; above 40 HRC switch to CBN/ceramic or grinding.
Can 42CrMo4 be welded?
Weldable with low-hydrogen consumables but requires 200–350 °C preheat, controlled interpass temperature and post-weld temper at 550–650 °C to avoid HAZ cracking.
Can 42CrMo4 be formed, bent or molded?
Hot forge 1100–850 °C then normalize; cold forming only in the annealed condition with generous radii — springback and cracking are high at ≥250 HB.
Manufacturability
The process limits FabDigit's quote engine applies to 42CrMo4. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better50 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair35 / 100 |
|---|---|
| Weldability | Better35 / 100 |
42CrMo4 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 | 0.38 – 0.45 | 0.42 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | |
| S42CrMo4; ≤0.005 for 42CrMoS4 grade the range is 0.020–0.040 | ≤ 0.04 | |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.3 | 0.22 |
| Fe | balance |
What surface finishes work on 42CrMo4?
No anodizing; protect with black oxide, phosphate + oil, zinc or hard-chrome plate, or nitride; polishes well to a mirror finish in the Q&T condition but rusts if left bare.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 42CrMo4 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 42CrMo4 cost?
42CrMo4 is a standard-cost steel ($$), cheaper than about 61% 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.
42CrMo4 — frequently asked
What is 42CrMo4 used for?
42CrMo4 is typically used for drive shafts and axles, gears and pinions, forged industrial parts, hydraulic cylinder rods, high-strength bolts and studs and crankshafts. In short: european Cr-Mo machining bar.
What is the yield strength of 42CrMo4?
42CrMo4 has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 850 MPa (123 ksi) — stronger than 71% of steel grades. Strength varies by condition: see the 17 listed tempers.
Is 42CrMo4 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine annealed (≤241 HB) or at 28–32 HRC with rigid setups, coated carbide, 80–160 m/min and generous coolant; above 40 HRC switch to CBN/ceramic or grinding.
Can 42CrMo4 be welded?
With care — weldability is rated fair (35/100). Weldable with low-hydrogen consumables but requires 200–350 °C preheat, controlled interpass temperature and post-weld temper at 550–650 °C to avoid HAZ cracking.
What surface finishes work on 42CrMo4?
No anodizing; protect with black oxide, phosphate + oil, zinc or hard-chrome plate, or nitride; polishes well to a mirror finish in the Q&T condition but rusts if left bare.
Can 42CrMo4 be formed, bent or molded?
Hot forge 1100–850 °C then normalize; cold forming only in the annealed condition with generous radii — springback and cracking are high at ≥250 HB.
What is the maximum service temperature of 42CrMo4?
42CrMo4 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.
What is the difference between 42CrMo4-HR and 42CrMo4-QT1100?
HR is the default condition — cheapest stock form for parts that will be heat treated after rough machining. QT1100: maximum standard Q&T class; highest strength but lowest toughness and highest cracking sensitivity. Yield strength is 550 MPa in HR versus 980 MPa in QT1100.
How much does 42CrMo4 cost?
42CrMo4 is a standard-cost steel ($$), cheaper than about 61% 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.
Can FabDigit make parts in 42CrMo4?
Yes — 42CrMo4 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)
- GB/T 3077 — Alloy structural steels (42CrMo) — SAC (2015)
- ASTM A29/A29M and SAE J404 (4140) — ASTM / SAE (2020)
- 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)
- 42CrMo4 / 1.7225 alloy steel datasheet — Ovako / Böhler / Dörrenberg (typical mill data) (2023)
- 42CrMo — Mysteel / 1688 (2026)
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.