Steel SCM420-CR (Cold rolled)
Supply condition
JIS SCM420
Cold-rolled strip for stamped/formed parts that will later be carburized.
Values for the CR condition
Other SCM420 tempers and conditions
SCM420 is listed in 7 conditions; see the grade overview at SCM420.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed (full / spheroidize annealed) | Softest condition — pick it for cold forging, deep machining or heavy upsetting before carburizing. | 360 | 560 | 27 | 163 HB | 7.9 % IACS |
HRDefault Hot rolled | Standard stock condition for bar and billet destined for machining, forging or carburizing. | 440 | 660 | 22 | 190 HB | — |
Normalized (≈870–920 °C, air cool) | Uniform fine-grain structure for consistent machining and predictable response to carburizing. | 470 | 720 | 21 | 15 HRC | 7.8 % IACS |
CRThis page Cold rolled | Cold-rolled strip for stamped/formed parts that will later be carburized. | 580 | 720 | 14 | 17 HRC | 7.8 % IACS |
Cold drawn | Cold-drawn bar giving close size tolerance, bright finish and higher as-supplied strength for screw-machine work. | 620 | 760 | 13 | 20 HRC | 7.8 % IACS |
Quenched and tempered | Through-hardened condition for shafts and fasteners where core strength, not surface wear, governs. | 760 | 980 | 17 | 31 HRC | — |
Carburized, hardened & low-temperature tempered (case 58–62 HRC) | The intended service condition for gears and pinions — hard wear-resistant case over a tough Cr-Mo core. | 900 | 1,150 | 12 | 60 HRC | — |
What is SCM420-CR?
SCM420-CR is SCM420 supplied in the CR condition — cold-rolled strip for stamped/formed parts that will later be carburized. SCM420-CR has a yield strength of 580 MPa (84.1 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 75% of steel grades. Elongation at break is 14% and the elastic modulus is 207 GPa (30 Msi). SCM420-CR 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). HR is the default condition FabDigit quotes; CR is available on request or by drawing note.
Advantages
- High strength — 580 MPa (84.1 ksi), better than 75% of steel grades
Limitations
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 78% of steel grades
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
SCM420-CR properties
Typical room-temperature values for SCM420-CR; 23 are specific to this condition. Other listed values are SCM420 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SCM420-CR 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).
Mechanical14
SCM420-CR has a yield strength of 580 MPa (84.1 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 75% of steel grades. Elongation at break is 14% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
SCM420-CR is rated for continuous service to 300°C (572 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
SCM420-CR 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 SCM420-CR takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
SCM420-CR's machinability is good (58/100, better than 75% of steel grades); weldability good (55/100); formability fair (50/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SCM420-CR
Is SCM420 easy to machine?
Machine in the annealed or normalized state (≈62 % of AISI 1212); carbide inserts, 120–180 m/min turning, finish-grind after carburizing to hold size.
Can SCM420 be welded?
Weldable with low-hydrogen consumables at CE ≈ 0.55: preheat 150–250 °C, control interpass, and PWHT at 600–650 °C; never weld a carburized surface.
Can SCM420 be formed, bent or molded?
Spheroidize-anneal for cold heading and cold forging; hot forge 1100–1200 °C and finish above 900 °C, then normalize before machining.
What surface finishes work on SCM420?
No anodizing — protect with black oxide, manganese phosphate, zinc or Ni plating; after carburizing use shot peening plus grinding for maximum bending fatigue life.
SCM420 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 G 4053 | 0.18 – 0.23 | 0.2 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.6 – 0.85 | 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 | — |
SCM420-CR — frequently asked
What is SCM420-CR used for?
SCM420-CR is typically used for gears, industrial drive shafts and pins. In short: carburizing Cr-Mo bar.
What is the yield strength of SCM420-CR?
SCM420-CR has a typical yield strength of 580 MPa (84.1 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 75% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is SCM420-CR easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machine in the annealed or normalized state (≈62 % of AISI 1212); carbide inserts, 120–180 m/min turning, finish-grind after carburizing to hold size.
Can SCM420-CR be welded?
Yes — weldability is rated good (55/100). Weldable with low-hydrogen consumables at CE ≈ 0.55: preheat 150–250 °C, control interpass, and PWHT at 600–650 °C; never weld a carburized surface.
What surface finishes work on SCM420-CR?
No anodizing — protect with black oxide, manganese phosphate, zinc or Ni plating; after carburizing use shot peening plus grinding for maximum bending fatigue life.
Can SCM420-CR be formed, bent or molded?
Spheroidize-anneal for cold heading and cold forging; hot forge 1100–1200 °C and finish above 900 °C, then normalize before machining.
What is the maximum service temperature of SCM420-CR?
SCM420-CR is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SCM420-HR and SCM420-CD?
HR is the default condition — standard stock condition for bar and billet destined for machining, forging or carburizing. CD: cold-drawn bar giving close size tolerance, bright finish and higher as-supplied strength for screw-machine work. Yield strength is 440 MPa in HR versus 620 MPa in CD.
Can FabDigit make parts in SCM420-CR?
Yes — SCM420-CR is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- JIS G 4053 — Low-alloyed steels for machine structural use — JSA (2016)
- ASTM A29/A29M and SAE J404 (4118/4120 equivalence) — ASTM / SAE (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing of Cr-Mo steels) — ASM International (1991)
- GB/T 3077 — (20CrMo / 20CrMnMo comparison grades) — SAC (2015)
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.