Steel A228
ASTM A228 · UNS K08500 · JIS SWP-A/B
A228 (music wire, SWP-A/B, UNS K08500) is cold-drawn high-carbon spring wire produced from patented rod, giving the highest tensile strength and most uniform fatigue behaviour of the common carbon spring wires.
Reference datasheet — A228 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 CD condition
A228 tempers and conditions
A228 is supplied in 6 conditions, soft to hard. CD is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
as-drawn, diameter 3.0–6.5 mm | Larger diameters where tensile strength drops with size; upper size limit of A228 supply. | 1,650 | 1,950 | 4 | 47 HRC | 8.6 % IACS |
JIS G 3522 piano wire, class A | Japanese/Asian equivalent supply class at the lower of the two JIS strength bands; common in Chinese and Japanese spring shops. | 1,850 | 2,180 | 3.5 | 50 HRC | 8.5 % IACS |
CDDefault Cold drawn | Standard stocked condition: bright, oiled, as-drawn coil for general small spring coiling. | 1,950 | 2,300 | 3 | 52 HRC | 8.6 % IACS |
JIS G 3522 piano wire, class B | Higher JIS strength band, closest match to ASTM A228 tensile requirements for the same diameter. | 1,980 | 2,320 | 3 | 52 HRC | 8.5 % IACS |
Stress relieved | Standard post-coiling bake for springs: raises elastic limit, reduces set and hydrogen risk, tensile essentially unchanged. | 2,050 | 2,320 | 3 | 52 HRC | 8.8 % IACS |
as-drawn, diameter ≤ 0.5 mm | Fine sizes reach the highest tensile levels of any carbon steel; used for micro springs and instrument strings. | 2,400 | 2,800 | 2 | 57 HRC | 8.3 % IACS |
Supply forms, finishes and certifications
Ways A228 is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
GALV | Zinc coated (galvanized) high-carbon spring wire | Surface finish |
SN | Tinned (tin-coated) music wire | Surface finish |
What is A228?
A228 (music wire, SWP-A/B, UNS K08500) is cold-drawn high-carbon spring wire produced from patented rod, giving the highest tensile strength and most uniform fatigue behaviour of the common carbon spring wires. Typical properties are about 1950 MPa yield and 2300 MPa tensile at 52 HRC with 3 % elongation, supplied in fine, heavy, stress-relieved, SWP-A/B, and galvanised conditions for small precision springs and wire forms. Elongation is low, service temperature is limited to roughly 120 °C and the wire has no corrosion resistance. Where diameters grow or coiling stresses are lower, oil-tempered A229 wire is the cheaper choice. A228 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,400°C (2,552 °F). A228 has a yield strength of 1,950 MPa (283 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 100% of steel grades. Elongation at break is 3% and the elastic modulus is 207 GPa (30 Msi).
What is A228 used for?
- Precision small coil springs
- Musical instrument strings
- Clock springs
- Wire forms
Advantages
- High strength — 1,950 MPa (283 ksi), better than 100% of steel grades
Limitations
- Limited service temperature — 120°C (248 °F), worse than 100% of steel grades
- Limited ductility — 3%, worse than 99% of steel grades
- Difficult to weld — 10/100, worse than 99% of steel grades
- Difficult to machine — 16/100, worse than 98% of steel grades
A228 properties
Typical room-temperature values for A228-CD; bars are the position among steel grades.
Physical3
A228 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical14
A228 has a yield strength of 1,950 MPa (283 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 100% of steel grades. Elongation at break is 3% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A228 is rated for continuous service to 120°C (248 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
A228 conducts electricity at 8.6 % IACS, better than 66% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of A228 takes about 27 MJ of energy and emits 2.1 kg of CO₂ — less than 59% of steel grades. Typical recycled content is 25%.
Manufacturability6
A228's machinability is poor (16/100, worse than 98% of steel grades); weldability not recommended (10/100); formability poor (30/100).
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. A228 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A228
Is A228 easy to machine?
Essentially not machined — grind or abrasive/EDM cut; wire is cut to length with shear or abrasive wheel, and cold-drawn hardness wrecks HSS tooling.
Can A228 be welded?
Do not weld the working part: any fusion or resistance weld anneals the drawn pearlite and creates a brittle low-strength zone; use mechanical hooks/loops or crimped terminals.
Can A228 be formed, bent or molded?
Coil cold on CNC spring machines with generous mandrel ratio (D/d ≥ 4), then stress relieve 200–260 °C for 20–30 min; sharp bends and tight hook radii cause longitudinal splitting.
A228 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 |
|---|---|---|
| Ccarbon level selected by diameter/strength class | 0.7 – 1 | 0.85 |
| Mn | 0.2 – 0.6 | 0.4 |
| Si | 0.1 – 0.3 | 0.2 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.03 | 0.01 |
| Fe | balance |
What surface finishes work on A228?
Ship oiled; for corrosion use phosphate+oil, tin or zinc coating, or mechanical galvanizing — after acid pickling or electroplating bake 190–230 °C for 4 h to avoid hydrogen embrittlement; shot peening markedly raises 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 A228 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- K08500
- JIS
- SWP-A/B
- Also called
- SWP-A
- Similar grades
- 70
How much does A228 cost?
A228 is a standard-cost steel ($$), cheaper than about 71% 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.
A228 — frequently asked
What is A228 used for?
A228 is typically used for precision small coil springs, musical instrument strings, clock springs and wire forms. In short: highest-strength carbon spring wire; best fatigue uniformity; low service temperature limit.
What is the yield strength of A228?
A228 has a typical yield strength of 1,950 MPa (283 ksi) and a tensile strength of 2,300 MPa (334 ksi) — stronger than 100% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is A228 easy to machine?
Not especially — machinability is rated poor (16/100, worse than 98% of steel grades). Essentially not machined — grind or abrasive/EDM cut; wire is cut to length with shear or abrasive wheel, and cold-drawn hardness wrecks HSS tooling.
Can A228 be welded?
Not readily — weldability is rated not recommended (10/100). Do not weld the working part: any fusion or resistance weld anneals the drawn pearlite and creates a brittle low-strength zone; use mechanical hooks/loops or crimped terminals.
What surface finishes work on A228?
Ship oiled; for corrosion use phosphate+oil, tin or zinc coating, or mechanical galvanizing — after acid pickling or electroplating bake 190–230 °C for 4 h to avoid hydrogen embrittlement; shot peening markedly raises fatigue life.
Can A228 be formed, bent or molded?
Coil cold on CNC spring machines with generous mandrel ratio (D/d ≥ 4), then stress relieve 200–260 °C for 20–30 min; sharp bends and tight hook radii cause longitudinal splitting.
What is the maximum service temperature of A228?
A228 is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A228-CD and A228 CD-FINE?
CD is the default condition — standard stocked condition: bright, oiled, as-drawn coil for general small spring coiling. CD-FINE: fine sizes reach the highest tensile levels of any carbon steel; used for micro springs and instrument strings. Yield strength is 1,950 MPa in CD versus 2,400 MPa in CD-FINE.
How much does A228 cost?
A228 is a standard-cost steel ($$), cheaper than about 71% 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
- ASTM A228/A228M — Standard Specification for Steel Wire, Music Spring Quality — ASTM International (2021)
- JIS G 3522 — Piano wire (SWP-A/SWP-B) — JSA (2014)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Spring Steels) — ASM International (1990)
- Design Handbook: Engineering Guide to Spring Design — Associated Spring / Barnes Group (1987)
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.