Steel 6145
AISI/SAE 6145 · UNS G61450
6145 is a medium-carbon chromium-vanadium alloy steel (UNS G61450) in the SAE-AISI 61xx family, stocked hot-rolled, annealed, normalized, cold-drawn, as-quenched and in quench-and-temper hardness bands from 28–32 up to 52–54 HRC.
Reference datasheet — 6145 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
6145 tempers and conditions
6145 is supplied in 10 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | Softest, most machinable condition; the normal supply state for bar that will be machined then quenched and tempered. | 420 | 670 | 22 | 197 HB | — |
Hot rolled | As-rolled mill condition; cheapest stock for parts that will be re-heat-treated after machining. | 460 | 760 | 18 | 217 HB | — |
Normalized | Uniform fine pearlitic structure for forgings before machining or final hardening; higher strength than annealed. | 615 | 940 | 18 | 27 HRC | — |
Cold drawn | Tight-tolerance bright bar with raised yield strength; pick for as-machined parts not needing heat treatment. | 690 | 790 | 12 | 229 HB | — |
Q&T 28–32 HRC | Tough general-purpose machine condition for shafts and highly stressed structural parts. | 900 | 1,000 | 18 | 30 HRC | — |
Q&T 34–38 HRC | Balanced strength/toughness for torsion bars, gear blanks and heavy-duty fasteners. | 1,080 | 1,180 | 15 | 36 HRC | — |
Q&T 40–44 HRC | High-strength condition for leaf/coil springs, punches and heavily loaded shafts. | 1,280 | 1,400 | 12 | 42 HRC | — |
Q&T 46–50 HRC | Classic spring/torsion-bar temper with maximum elastic limit at usable toughness. | 1,480 | 1,620 | 10 | 48 HRC | — |
Q&T 52–54 HRC | Maximum strength temper for hand tools and wear parts; notch-sensitive, avoid stress raisers. | 1,650 | 1,830 | 8 | 53 HRC | — |
As-quenched | Intermediate process state only — must be tempered promptly; brittle and prone to quench cracking. | 1,650 | 2,100 | 2 | 59 HRC | 6.6 % IACS |
What is 6145?
6145 is a medium-carbon chromium-vanadium alloy steel (UNS G61450) in the SAE-AISI 61xx family, stocked hot-rolled, annealed, normalized, cold-drawn, as-quenched and in quench-and-temper hardness bands from 28–32 up to 52–54 HRC. It has higher hardenability than 6118/6120 and is used for springs, highly stressed shafts and high-strength fasteners; annealed reference values are 420 MPa yield, 670 MPa tensile, 22 % elongation and 197 HB (92 HRB). Weldability is poor (score 30), machinability is 52 and formability 45, service tops out near 400 °C and there is no corrosion resistance; 5160 is the common spring alternative. 6145 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). 6145 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 670 MPa (97.2 ksi) — weaker than 53% of steel grades. Elongation at break is 22% and the elastic modulus is 205 GPa (29.7 Msi).
What is 6145 used for?
- springs
- shafts
- high-strength fasteners
6145 properties
Typical room-temperature values for 6145-A; bars are the position among steel grades.
Physical3
6145 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
6145 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 670 MPa (97.2 ksi) — weaker than 53% of steel grades. Elongation at break is 22% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
6145 is rated for continuous service to 400°C (752 °F). It conducts heat at 45 W/m·K (26 BTU/hr·ft·°F), better than 66% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
6145 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 6145 takes about 29 MJ of energy and emits 2.1 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 30%.
Manufacturability7
6145's machinability is fair (52/100, better than 52% of steel grades); weldability poor (30/100); formability fair (45/100).
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. 6145 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 6145
Is 6145 easy to machine?
Machine in the annealed or ≤32 HRC condition with rigid setups, carbide tooling and generous coolant; above 40 HRC switch to grinding or CBN.
Can 6145 be welded?
Poor weldability (CE ≈0.85): preheat 250–350 °C, use low-hydrogen consumables, and temper immediately after welding to avoid martensitic cracking.
Can 6145 be formed, bent or molded?
Cold-form or coil only in the annealed state; springs are usually hot-coiled or coiled from annealed bar then quenched and tempered, with stress relief after coiling.
6145 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 | 0.43 – 0.48 | 0.46 |
| Mn | 0.7 – 0.9 | 0.8 |
| Si | 0.15 – 0.35 | 0.25 |
| Cr | 0.8 – 1.1 | 0.95 |
| V0.15 % minimum per SAE J404 | ≥ 0.15 | 0.18 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 6145?
No anodizing — protect with black oxide, phosphate + oil, zinc or Zn-Ni plating (bake at 190–220 °C for hydrogen relief); shot peening markedly raises spring fatigue life.
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 6145 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G61450
How much does 6145 cost?
6145 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.
6145 — frequently asked
What is 6145 used for?
6145 is typically used for springs, shafts and high-strength fasteners. In short: higher hardenability than 6120; cr-V spring and shaft steel; poor weldability.
What is the yield strength of 6145?
6145 has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 670 MPa (97.2 ksi) — weaker than 53% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 6145 easy to machine?
Reasonably — machinability is rated fair (52/100, better than 52% of steel grades). Machine in the annealed or ≤32 HRC condition with rigid setups, carbide tooling and generous coolant; above 40 HRC switch to grinding or CBN.
Can 6145 be welded?
Not readily — weldability is rated poor (30/100). Poor weldability (CE ≈0.85): preheat 250–350 °C, use low-hydrogen consumables, and temper immediately after welding to avoid martensitic cracking.
What surface finishes work on 6145?
No anodizing — protect with black oxide, phosphate + oil, zinc or Zn-Ni plating (bake at 190–220 °C for hydrogen relief); shot peening markedly raises spring fatigue life.
Can 6145 be formed, bent or molded?
Cold-form or coil only in the annealed state; springs are usually hot-coiled or coiled from annealed bar then quenched and tempered, with stress relief after coiling.
What is the maximum service temperature of 6145?
6145 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 6145-A and 6145 QT52-54?
A is the default condition — softest, most machinable condition; the normal supply state for bar that will be machined then quenched and tempered. QT52-54: maximum strength temper for hand tools and wear parts; notch-sensitive, avoid stress raisers. Yield strength is 420 MPa in A versus 1,650 MPa in QT52-54.
How much does 6145 cost?
6145 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)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating — ASM International (1991)
- Machinery's Handbook, 31st ed. — Industrial Press (2020)
- GB/T 1222 (50CrVA) — SAC (2016)
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.