Steel 5120 · supply condition · default condition
Steel 5120-HR
Properties of the HR condition, compared with the other 5120 tempers.
Standard stock form for bar and billet destined for forging, machining and subsequent carburizing.
What is 5120-HR?
5120-HR is 5120 supplied in the HR condition — standard stock form for bar and billet destined for forging, machining and subsequent carburizing. 5120-HR has a yield strength of 295 MPa (42.8 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 87% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi). 5120-HR 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).
Advantages
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- Easy to machine — 62/100, better than 89% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 76% of steel grades
Limitations
- Low strength — 295 MPa (42.8 ksi), worse than 87% of steel grades
5120-HR properties
Typical room-temperature values for 5120-HR — 9 properties are specific to this condition; the rest are grade-level values shared by every 5120 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
5120-HR 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).
Mechanical14
5120-HR has a yield strength of 295 MPa (42.8 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 87% of steel grades. Elongation at break is 25% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
5120-HR is rated for continuous service to 350°C (662 °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-HR conducts electricity at 7.8 % IACS, worse than 58% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 5120-HR 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-HR's machinability is good (62/100, better than 89% of steel grades); weldability good (60/100); formability good (58/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 5120 tempers and conditions
5120 is also supplied in 6 other conditions. The full side-by-side table is on the 5120 overview.
- HRDefaultStandard stock form for bar and billet destined for forging, machining and subsequent carburizing.295 MPa yield · 145 HB
- CarburizedThe intended service condition: hard wear- and pitting-resistant case over a tough low-carbon core for gears, splines and pins.700 MPa yield · 60 HRC
- Q&TThrough-hardened low-carbon martensite for small tough parts where full case hardening is not required.640 MPa yield · 23 HRC
- CDChoose for close-tolerance, bright-finish bar with higher yield strength and better surface for turned parts.480 MPa yield · 170 HB
- NormalizedUniform fine-grain structure and stable machining response prior to carburizing; standard pre-treatment for forgings.330 MPa yield · 155 HB
- AnnealedSoftest and most machinable/formable state; use before heavy cold forming or deep drilling.280 MPa yield · 131 HB
Working with 5120-HR
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-HR — frequently asked
What is 5120-HR used for?
5120-HR is typically used for gears, pins and shafts. In short: carburizing Cr-Mn bar.
What is the yield strength of 5120-HR?
5120-HR has a typical yield strength of 295 MPa (42.8 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 87% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 5120-HR easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% 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-HR be welded?
Yes — weldability is rated good (60/100). Weldable with low-hydrogen consumables at ~150–250 °C preheat; avoid welding carburized surfaces and stress-relieve afterwards.
What surface finishes work on 5120-HR?
No anodizing; protect with oil, phosphate, black oxide or zinc/nickel plating — bake after plating to avoid hydrogen embrittlement in hardened parts.
Can 5120-HR 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-HR?
5120-HR is rated for continuous use to about 350°C (662 °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-HR?
Yes — 5120-HR 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
- 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.