Steel 5120-CR (Cold rolled)
Supply condition
AISI/SAE 5120 · UNS G51200 · JIS SCr420
Cold-rolled strip for stamped and formed parts that will be case-hardened after forming.
Values for the CR condition
Other 5120 tempers and conditions
5120 is listed in 7 conditions; see the grade overview at 5120.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed (soft annealed, ~870 °C furnace cool) | Softest and most machinable/formable state; use before heavy cold forming or deep drilling. | 280 | 450 | 28 | 131 HB | 7.9 % IACS |
HRDefault Hot rolled | Standard stock form for bar and billet destined for forging, machining and subsequent carburizing. | 295 | 470 | 25 | 145 HB | 7.8 % IACS |
Normalized (~900 °C, air cool) | Uniform fine-grain structure and stable machining response prior to carburizing; standard pre-treatment for forgings. | 330 | 520 | 24 | 155 HB | 7.8 % IACS |
CRThis page Cold rolled | Cold-rolled strip for stamped and formed parts that will be case-hardened after forming. | 400 | 520 | 18 | 160 HB | 7.8 % IACS |
Cold drawn | Choose for close-tolerance, bright-finish bar with higher yield strength and better surface for turned parts. | 480 | 570 | 15 | 170 HB | 7.8 % IACS |
Quenched and tempered | Through-hardened low-carbon martensite for small tough parts where full case hardening is not required. | 640 | 830 | 16 | 23 HRC | — |
Carburized, quenched & low-temper (case 0.5–1.5 mm, 58–62 HRC surface) | The intended service condition: hard wear- and pitting-resistant case over a tough low-carbon core for gears, splines and pins. | 700 | 900 | 11 | 60 HRC | — |
What is 5120-CR?
5120-CR is 5120 supplied in the CR condition — cold-rolled strip for stamped and formed parts that will be case-hardened after forming. 5120-CR has a yield strength of 400 MPa (58 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 60% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi). 5120-CR 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). HR is the default condition FabDigit quotes; CR is available on request or by drawing note.
Advantages
- Easy to machine — 65/100, better than 93% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Forms and bends easily — 62/100, better than 78% of steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
5120-CR properties
Typical room-temperature values for 5120-CR; 22 are specific to this condition. Other listed values are 5120 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
5120-CR 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
5120-CR has a yield strength of 400 MPa (58 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 60% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
5120-CR is rated for continuous service to 300°C (572 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
5120-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 5120-CR takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
5120-CR's machinability is good (65/100, better than 93% of steel grades); weldability good (58/100); formability good (62/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 5120-CR
Is 5120 easy to machine?
Machines well in annealed/normalized state (~65% of 1212); rough-machine before carburizing and leave grinding stock for post-hardening finishing.
Can 5120 be welded?
Weldable with low-hydrogen consumables at ~150–250 °C preheat; avoid welding carburized surfaces and stress-relieve afterwards.
Can 5120 be formed, bent or molded?
Good cold formability when annealed — used for cold-headed and stamped blanks; hot forge 1150–850 °C then normalize.
What surface finishes work on 5120?
No anodizing; protect with oil, phosphate, black oxide or zinc/nickel plating — bake after plating to avoid hydrogen embrittlement in hardened parts.
5120 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 | 0.17 – 0.22 | 0.2 |
| Mn | 0.7 – 0.9 | 0.8 |
| Si | 0.15 – 0.35 | 0.25 |
| Cr | 0.7 – 0.9 | 0.8 |
| P | ≤ 0.04 | — |
| Smax; 5120H/resulfurized variants differ | ≤ 0.04 | — |
| Fe | balance | — |
5120-CR — frequently asked
What is 5120-CR used for?
5120-CR is typically used for gears, pins and shafts. In short: carburizing Cr-Mn bar.
What is the yield strength of 5120-CR?
5120-CR has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 5120-CR easy to machine?
Reasonably — machinability is rated good (65/100, better than 93% of steel grades). Machines well in annealed/normalized state (~65% of 1212); rough-machine before carburizing and leave grinding stock for post-hardening finishing.
Can 5120-CR be welded?
Yes — weldability is rated good (58/100). Weldable with low-hydrogen consumables at ~150–250 °C preheat; avoid welding carburized surfaces and stress-relieve afterwards.
What surface finishes work on 5120-CR?
No anodizing; protect with oil, phosphate, black oxide or zinc/nickel plating — bake after plating to avoid hydrogen embrittlement in hardened parts.
Can 5120-CR be formed, bent or molded?
Good cold formability when annealed — used for cold-headed and stamped blanks; hot forge 1150–850 °C then normalize.
What is the maximum service temperature of 5120-CR?
5120-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 5120-HR and 5120-CD?
HR is the default condition — standard stock form for bar and billet destined for forging, machining and subsequent carburizing. CD: choose for close-tolerance, bright-finish bar with higher yield strength and better surface for turned parts. Yield strength is 295 MPa in HR versus 480 MPa in CD.
Can FabDigit make parts in 5120-CR?
Yes — 5120-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
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- GB/T 3077 (20Cr) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals and Processes — ASM International (2013)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
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.