6150 is a chromium vanadium spring and tool steel. Vanadium refines the grain and forms carbides that raise fatigue strength and wear resistance, which is why 6150 shows up in springs, torsion bars and hand tools that must flex repeatedly without setting.
It through hardens well in moderate sections and tempers to a wide range of strength levels.
Stocked as bar, billet and wire, supplied annealed for forming and machining or heat treated to the ordered condition.
Sizes and stock
- Round bar: through 5" DIA
- Sheet / plate: through 0.375" THK
- Custom shapes and forgings: per request
Processing capabilities
- Vacuum melted (VAR / VIM-VAR) stock with full melt traceability
- Normalize, anneal, quench and temper to the ordered condition
- Saw cutting, trepanning, gun drilling and rough machining
- Magnetic particle and ultrasonic inspection to AMS 2301 / AMS 2154 on request
Specifications
Material is released to the applicable specification with mill test reports and, on request, independent lab verification.
Why engineers specify 6150
- High fatigue strength for spring service
- Vanadium refined grain with good wear resistance
- Good hardenability and toughness
- Long service record in springs and tooling
Nominal chemistry
Percent by weight, nominal composition per the governing specification. The mill test report for your heat is the controlling document.
Typical applications
- Coil and leaf springs
- Torsion bars
- Hand tools and chisels
- Gears and shafts in wear service
Fabrication notes
Machining
Best machined in the annealed or normalized-and-tempered condition, then heat treated to final strength. Rough machining before hardening, with a finish pass after temper, controls distortion on long or thin sections. We can supply rough turned, trepanned or gun drilled stock so your first operation starts closer to net shape.
Welding
Weldable with low hydrogen practice, preheat appropriate to carbon equivalent and section size, and a post weld stress relief or full re-heat treat. For high strength conditions the weld and heat affected zone should be re-treated to restore properties.
Forming
Hot work in the annealed condition. Cold forming is limited at high hardness, so bend and form before hardening and follow with stress relief where the geometry is tight.
6150 compared with similar grades
5160
Common leaf spring steel without vanadium, lower fatigue performance.
4340
Better toughness at high strength, less suited to spring duty.
Designations and cross reference
- Material family
- Alloy Steels
- Werkstoff (W.Nr)
- 1.8159
- EN designation
- 51CrV4
Working from an obsolete, foreign or superseded designation? Send it over and we will cross reference it to a current grade and specification.
Quality, testing and traceability
Supplied aircraft quality with mill test reports, melt and heat traceability, and, on request, magnetic particle inspection to AMS 2301 or AMS 2300, ultrasonic inspection to AMS 2154, chemical assay, hardness and full mechanical testing.
We are AS9100D and ISO 9001:2015 registered. If our stock does not already carry the inspection your specification requires, we can quote the material with that work performed. More on our quality system
Available forms
Custom sizes converted from billet, plus saw cut, waterjet and near-net blanks. See custom conversions
6150 frequently asked questions
What is 6150?
6150 is a chromium vanadium spring and tool steel. Vanadium refines the grain and forms carbides that raise fatigue strength and wear resistance, which is why 6150 shows up in springs, torsion bars and hand tools that must flex repeatedly without setting.
What forms is 6150 available in?
We supply 6150 in bar, sheet, plate, forging. Custom sizes are converted from billet, and we can provide saw cut, waterjet or near net blanks so material arrives closer to your finished part.
What is the UNS or equivalent designation for 6150?
6150 is designated Werkstoff 1.8159, EN 51CrV4. If your drawing calls out an obsolete or foreign designation we can cross reference it and confirm the equivalent before you order.
What specifications can 6150 be supplied to?
Commonly ordered specifications include AMS 6448, AMS 6455, AMS 6450. Material is released to the specification and condition on your purchase order, with mill test reports supplied as standard.
Can you cut 6150 to size?
Yes. Saw cutting, waterjet, laser and shearing are available, along with trepanning, gun drilling, lathe turning and CNC machining, so you can order blanks or rough machined pieces rather than full lengths.
Do you provide test reports and additional testing on 6150?
Every order ships with mill test reports and heat traceability. If your print calls for ultrasonic inspection, penetrant dye, magnetic particle, chemical assay, micrography, hardness or mechanical testing and our stock does not already carry it, we can quote the material with that work performed.
Can 6150 be supplied to DFARS domestic melt requirements?
Tell us at quote stage if the order is DFARS or domestic melt restricted and we will confirm availability against that requirement before you commit.
What do you need to quote 6150?
Grade, form, dimensions, quantity, specification and condition, plus any testing or certification requirements and the date you need it. Send a drawing if you have one. Quotes are typically ready within 24 hours.
How does 6150 compare with 5160?
Common leaf spring steel without vanadium, lower fatigue performance.