Steel SCM440
JIS SCM440 · EN 42CrMo4
SCM440 is the JIS G4053 chromium–molybdenum through-hardening structural steel, essentially interchangeable with AISI 4140 / DIN 42CrMo4 / GB 42CrMo.
Values for the HR condition
SCM440 tempers and conditions
SCM440 is supplied in 11 conditions, soft to hard. HR is the default FabDigit quotes; the values on this page are for it.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full/spheroidize annealed, softest condition | Choose for heavy machining, cold forming or deep-hole drilling before final hardening. | 415 | 655 | 25 | 197 HB | — |
Cold rolled | Thin strip/sheet stock with tight thickness and a clean surface, for stamped parts later hardened. | 550 | 750 | 13 | 17 HRC | 7.8 % IACS |
HRDefault Hot rolled | Cheapest stock form for parts that will be machined then heat treated by the fabricator. | 590 | 880 | 17 | 25 HRC | — |
860–880 °C air cooled | Uniform fine grain and mid-range strength; used as pre-treatment before machining/hardening or as final state for low-stress parts. | 655 | 1,020 | 17.5 | 32 HRC | — |
Quenched and high-temperature tempered | Maximum toughness / NACE-friendly hardness cap for pressure and downhole components. | 720 | 860 | 20 | 24 HRC | — |
Cold drawn | Pick for near-net-size shafts and turned parts needing good surface finish and straightness without further grinding. | 750 | 900 | 12 | 26 HRC | — |
Q&T then gas/plasma nitrided (500–540 °C) | Low-distortion hard case (~0.2–0.5 mm, 550–650 HV) for wear and fatigue-critical shafts and screws. | 850 | 980 | 12 | 55 HRC | 7.8 % IACS |
Quenched and tempered | Standard supply condition for shafts, gears and machine parts needing balanced strength and toughness. | 880 | 1,000 | 16 | 30 HRC | — |
Induction hardened | For journals, splines and guideways needing a wear-resistant 52–58 HRC case over a tough Q&T core. | 880 | 1,000 | 14 | 55 HRC | 7.8 % IACS |
Quenched and medium-temperature tempered | Higher-strength shafts, high-tensile bolting and moulds where toughness is still needed. | 1,060 | 1,180 | 14 | 36 HRC | — |
Quenched and low-temperature tempered | Highest strength/wear condition for pins, dies and rams; accept low impact toughness and hydrogen-embrittlement risk when plating. | 1,280 | 1,400 | 11 | 42 HRC | — |
What is SCM440?
SCM440 is the JIS G4053 chromium–molybdenum through-hardening structural steel, essentially interchangeable with AISI 4140 / DIN 42CrMo4 / GB 42CrMo. It is the workhorse for shafts, gears, bolts, hydraulic rams, spindles and tooling holders because it combines deep hardenability, high quenched-and-tempered strength (up to ~1400 MPa) and good toughness at moderate cost. Limits are poor corrosion resistance (needs coating/oil), reduced weldability requiring preheat and post-weld tempering, and loss of strength above ~400 °C (never use above the tempering temperature). SCM440 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,416°C (2,581 °F). SCM440 has a yield strength of 590 MPa (85.6 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 76% of steel grades. Elongation at break is 17% and the elastic modulus is 210 GPa (30.5 Msi).
What is SCM440 used for?
- Drive shafts
- Crankshafts
- Industrial bolts
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
- High strength — 590 MPa (85.6 ksi), better than 76% of steel grades
SCM440 properties
Typical room-temperature values for SCM440-HR; bars are the position among steel grades.
Physical3
SCM440 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,416°C (2,581 °F).
Mechanical16
SCM440 has a yield strength of 590 MPa (85.6 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 76% of steel grades. Elongation at break is 17% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
SCM440 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
SCM440 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 SCM440 takes about 29 MJ of energy and emits 2.1 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability6
SCM440's machinability is good (55/100, better than 62% of steel grades); weldability fair (40/100); 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. SCM440 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SCM440
Is SCM440 easy to machine?
Machines best at 200–280 HB with coated carbide, ~120–180 m/min turning; above 40 HRC switch to CBN/ceramic or grind.
Can SCM440 be welded?
Weldable with low-hydrogen consumables but requires 250–350 °C preheat, interpass control and immediate PWHT/temper at 600–650 °C to avoid HAZ cracking.
Can SCM440 be formed, bent or molded?
Hot forge at 1100–1200 °C then normalize; cold bending only in the annealed condition with generous radii (≥3t).
Manufacturability
The process limits FabDigit's quote engine applies to SCM440. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Better55 / 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 | Better40 / 100 |
SCM440 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 |
|---|---|---|
| CJIS G4053 SCM440 | 0.38 – 0.43 | 0.4 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Cr | 0.9 – 1.2 | 1.05 |
| Mo | 0.15 – 0.3 | 0.22 |
| Niresidual, max | ≤ 0.25 | |
| Curesidual, max | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on SCM440?
Not corrosion resistant — use black oxide, phosphate, Zn or Zn-Ni plating, or nitriding; bake 190–220 °C for 4 h after plating parts above ~35 HRC to relieve hydrogen.
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 SCM440 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does SCM440 cost?
SCM440 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.
SCM440 — frequently asked
What is SCM440 used for?
SCM440 is typically used for drive shafts, crankshafts and industrial bolts. In short: workhorse Cr-Mo Japanese bar.
What is the yield strength of SCM440?
SCM440 has a typical yield strength of 590 MPa (85.6 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 76% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is SCM440 easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines best at 200–280 HB with coated carbide, ~120–180 m/min turning; above 40 HRC switch to CBN/ceramic or grind.
Can SCM440 be welded?
With care — weldability is rated fair (40/100). Weldable with low-hydrogen consumables but requires 250–350 °C preheat, interpass control and immediate PWHT/temper at 600–650 °C to avoid HAZ cracking.
What surface finishes work on SCM440?
Not corrosion resistant — use black oxide, phosphate, Zn or Zn-Ni plating, or nitriding; bake 190–220 °C for 4 h after plating parts above ~35 HRC to relieve hydrogen.
Can SCM440 be formed, bent or molded?
Hot forge at 1100–1200 °C then normalize; cold bending only in the annealed condition with generous radii (≥3t).
What is the maximum service temperature of SCM440?
SCM440 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 SCM440-HR and SCM440-IH?
HR is the default condition — cheapest stock form for parts that will be machined then heat treated by the fabricator. IH: for journals, splines and guideways needing a wear-resistant 52–58 HRC case over a tough Q&T core. Yield strength is 590 MPa in HR versus 880 MPa in IH.
How much does SCM440 cost?
SCM440 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 SCM440?
Yes — SCM440 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
- JIS G 4053 — Low-alloyed structural steels for machine structural use — JSA (2016)
- GB/T 3077 — Alloy structural steels (42CrMo) — SAC (2015)
- ASTM A29/A29M & A322 (AISI 4140) — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- 42CrMo4 / 4140 heat-treatable steel datasheet — Böhler / Ovako (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.