Steel 6120
AISI/SAE 6120 · UNS G61200
6120 is a low-carbon chromium-vanadium case-hardening steel (UNS G61200) in the SAE-AISI 61xx family, stocked hot-rolled, annealed, spheroidize-annealed, normalized, normalized-and-tempered, cold-drawn, quenched-and-tempered and carburized.
Reference datasheet — 6120 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the A condition
6120 tempers and conditions
6120 is supplied in 9 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize Annealed | Choose for severe cold heading/upsetting of fastener and gear blanks. | 340 | 530 | 32 | 150 HB | 7.8 % IACS |
ADefault Solution annealed | Standard soft stocking condition for machining, cold forming and carburizing blanks. | 370 | 570 | 29 | 163 HB | — |
Hot rolled | Cheapest mill condition for bar and forging stock that will be re-heat-treated anyway. | 400 | 620 | 24 | 179 HB | 7.5 % IACS |
Normalized and tempered | Stress-relieved normalized bar for structural parts needing dimensional stability and impact toughness. | 420 | 620 | 27 | 180 HB | 7.5 % IACS |
Normalized | Uniform fine-grain structure and better toughness than as-rolled; usual pre-treatment before carburizing or machining of forgings. | 440 | 655 | 25 | 190 HB | 7.5 % IACS |
Cold drawn | Pick for tight-tolerance bright bar with higher yield strength and better surface without heat treatment. | 600 | 700 | 13 | 207 HB | — |
Q&T 22–28 HRC | Through-hardened condition for tough shafts and structural fasteners where a moderate strength level is enough. | 650 | 830 | 20 | 25 HRC | — |
Carburized, Quenched and Tempered | The intended service condition for gears, pinions and cams — hard wear-resistant case over a tough Cr-V core. | 750 | 1,000 | 12 | 60 HRC | — |
Q&T 30–35 HRC | Highest practical through-hardened strength for this 0.20 % C grade; use in small sections only. | 820 | 1,000 | 16 | 32 HRC | — |
What is 6120?
6120 is a low-carbon chromium-vanadium case-hardening steel (UNS G61200) in the SAE-AISI 61xx family, stocked hot-rolled, annealed, spheroidize-annealed, normalized, normalized-and-tempered, cold-drawn, quenched-and-tempered and carburized. It is chosen for gears, shafts and structural fasteners because vanadium holds a fine grain through carburizing while the core stays tough: 370 MPa yield, 570 MPa tensile, 29 % elongation, 163 HB (84 HRB) and formability 58 in the reference condition. Hardenability is only moderate, bare corrosion resistance is nil and service is limited to about 425 °C; 8620 is the usual alternative for deeper case hardening at lower alloy cost. 6120 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). 6120 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 70% of steel grades. Elongation at break is 29% and the elastic modulus is 205 GPa (29.7 Msi).
What is 6120 used for?
- gears
- structural fasteners
- shafts
Advantages
- Ductile — tolerates forming and impact — 29%, better than 91% of steel grades
6120 properties
Typical room-temperature values for 6120-A; bars are the position among steel grades.
Physical3
6120 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).
Mechanical13
6120 has a yield strength of 370 MPa (53.7 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 70% of steel grades. Elongation at break is 29% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
6120 is rated for continuous service to 425°C (797 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
6120 conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of 6120 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
6120's machinability is fair (52/100, better than 52% of steel grades); weldability good (55/100); 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.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. 6120 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 6120
Is 6120 easy to machine?
Machines well annealed or normalized (~60 % of 1212) with carbide tooling and flood coolant; finish-grind after carburizing since the case is essentially unmachinable.
Can 6120 be welded?
Weldable with low-hydrogen consumables; preheat 150–250 °C and post-weld temper, and never weld carburized surfaces.
Can 6120 be formed, bent or molded?
Cold head and bend in the annealed or spheroidized condition; hot forge 1150–1200 °C and finish above ~900 °C, then normalize to restore grain size.
6120 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 |
| V0.10 % min per SAE J404 | ≥ 0.1 | 0.15 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 6120?
No corrosion resistance bare — use black oxide, phosphate-and-oil, zinc or hard chrome; shot-peen carburized gear roots for fatigue life and bake after plating to avoid hydrogen embrittlement.
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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel 6120 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G61200
How much does 6120 cost?
6120 is a budget-cost steel ($), cheaper than about 90% 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.
6120 — frequently asked
What is 6120 used for?
6120 is typically used for gears, structural fasteners and shafts. In short: fine-grain carburizing grade; tough Cr-V gear core; moderate hardenability only.
What is the yield strength of 6120?
6120 has a typical yield strength of 370 MPa (53.7 ksi) and a tensile strength of 570 MPa (82.7 ksi) — weaker than 70% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is 6120 easy to machine?
Reasonably — machinability is rated fair (52/100, better than 52% of steel grades). Machines well annealed or normalized (~60 % of 1212) with carbide tooling and flood coolant; finish-grind after carburizing since the case is essentially unmachinable.
Can 6120 be welded?
Yes — weldability is rated good (55/100). Weldable with low-hydrogen consumables; preheat 150–250 °C and post-weld temper, and never weld carburized surfaces.
What surface finishes work on 6120?
No corrosion resistance bare — use black oxide, phosphate-and-oil, zinc or hard chrome; shot-peen carburized gear roots for fatigue life and bake after plating to avoid hydrogen embrittlement.
Can 6120 be formed, bent or molded?
Cold head and bend in the annealed or spheroidized condition; hot forge 1150–1200 °C and finish above ~900 °C, then normalize to restore grain size.
What is the maximum service temperature of 6120?
6120 is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 6120-A and 6120 QT-32?
A is the default condition — standard soft stocking condition for machining, cold forming and carburizing blanks. QT-32: highest practical through-hardened strength for this 0.20 % C grade; use in small sections only. Yield strength is 370 MPa in A versus 820 MPa in QT-32.
How much does 6120 cost?
6120 is a budget-cost steel ($), cheaper than about 90% 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.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- SAE J1268 / ASTM A304 — Hardenability requirements for alloy steel bars — SAE / ASTM (2016)
- 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-V steels) — ASM International (1991)
- Machinery's Handbook, 31st ed. (machinability ratings, alloy steel heat treatment) — Industrial Press (2020)
- GB/T 3077 (20CrV comparison grade) — SAC (2015)
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.