Steel A229
ASTM A229 · JIS SWO-A/B, SWO-A
A229 (SWO-A/B, 1065–1075 / 65Mn analogue) is carbon spring wire hardened and tempered in-process — oil-tempered — before coiling, so springs are wound from wire already at strength.
Reference datasheet — A229 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 CL1 condition
A229 tempers and conditions
A229 is supplied in 3 conditions, soft to hard. CL1 is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
CL1Default Class I | Default economy oil-tempered wire for static and lightly cycled springs; widest diameter availability and lowest price. | 1,320 | 1,550 | 7 | 45 HRC | — |
Class I, stress-relieved after coiling | Standard finished-spring condition: low-temperature bake after forming restores elastic limit, reduces set and relaxation. | 1,390 | 1,540 | 7 | 44 HRC | 9 % IACS |
Class II | Pick when higher stress or smaller spring envelope is needed; ~10 % higher tensile than Class I at the cost of coilability. | 1,450 | 1,690 | 6 | 48 HRC | — |
What is A229?
A229 (SWO-A/B, 1065–1075 / 65Mn analogue) is carbon spring wire hardened and tempered in-process — oil-tempered — before coiling, so springs are wound from wire already at strength. Typical values are about 1320 MPa yield, 1550 MPa tensile, 430 HB / 45 HRC with 7 % elongation, supplied as Class I, Class II and stress-relieved Class I wire for general mechanical springs. It costs less than music wire but has lower fatigue uniformity, minimal corrosion resistance (score 10), poor weldability (score 15) and a service limit near 150 °C. For high-stress or elevated-temperature duty, step up to A401 chrome-silicon wire. A229 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). A229 has a yield strength of 1,320 MPa (191 ksi) and a tensile strength of 1,550 MPa (225 ksi) — stronger than 95% of steel grades. Elongation at break is 7% and the elastic modulus is 207 GPa (30 Msi).
What is A229 used for?
- General coil springs
- Upholstery springs
- Mattress springs
Advantages
- High strength — 1,320 MPa (191 ksi), better than 95% of steel grades
Limitations
- Limited service temperature — 150°C (302 °F), worse than 99% of steel grades
- Low fracture toughness — 25 MPa·√m (22.8 ksi·√in), worse than 97% of steel grades
- Difficult to machine — 20/100, worse than 97% of steel grades
- Limited ductility — 7%, worse than 96% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
A229 properties
Typical room-temperature values for A229-CL1; bars are the position among steel grades.
Physical3
A229 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
A229 has a yield strength of 1,320 MPa (191 ksi) and a tensile strength of 1,550 MPa (225 ksi) — stronger than 95% of steel grades. Elongation at break is 7% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
A229 is rated for continuous service to 150°C (302 °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
A229 conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of A229 takes about 29 MJ of energy and emits 2.2 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 20%.
Manufacturability8
A229's machinability is poor (20/100, worse than 97% of steel grades); weldability poor (15/100); 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. A229 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A229
Is A229 easy to machine?
Supplied at 40–50 HRC, so cut with abrasive wheels or carbide/CBN and grind ends rather than turn or mill; annealing to machine destroys spring properties.
Can A229 be welded?
Effectively non-weldable for structural purposes — high carbon gives hard, crack-prone HAZ and local loss of temper; use mechanical hooks, loops or crimped ends instead.
Can A229 be formed, bent or molded?
Coil cold on standard spring machines (Class I coils easier than Class II), then stress relieve 230–290 °C for 20–30 min; keep bend radii generous and avoid sharp hook transitions.
A229 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 |
|---|---|---|
| Cheat analysis range per ASTM A229; mill selects grade within range for the ordered tensile class | 0.55 – 0.85 | 0.68 |
| Mn | 0.3 – 1.2 | 0.75 |
| Si | 0.15 – 0.35 | 0.25 |
| P | ≤ 0.04 | |
| S | ≤ 0.05 | |
| Fe | balance |
What surface finishes work on A229?
Not anodizable; protect with oil, phosphate + oil, black oxide, zinc/mechanical galvanizing or powder coat — bake at ~200 °C after any acid pickling or electroplating to avoid hydrogen embrittlement; shot peening markedly improves 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 A229 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- JIS
- SWO-A/BSWO-A
- Similar grades
- 1065-107565Mn
How much does A229 cost?
A229 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.
A229 — frequently asked
What is A229 used for?
A229 is typically used for general coil springs, upholstery springs and mattress springs. In short: best cost-to-strength spring wire; oil-tempered, no post-hardening; weaker fatigue than music wire.
What is the yield strength of A229?
A229 has a typical yield strength of 1,320 MPa (191 ksi) and a tensile strength of 1,550 MPa (225 ksi) — stronger than 95% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is A229 easy to machine?
Not especially — machinability is rated poor (20/100, worse than 97% of steel grades). Supplied at 40–50 HRC, so cut with abrasive wheels or carbide/CBN and grind ends rather than turn or mill; annealing to machine destroys spring properties.
Can A229 be welded?
Not readily — weldability is rated poor (15/100). Effectively non-weldable for structural purposes — high carbon gives hard, crack-prone HAZ and local loss of temper; use mechanical hooks, loops or crimped ends instead.
What surface finishes work on A229?
Not anodizable; protect with oil, phosphate + oil, black oxide, zinc/mechanical galvanizing or powder coat — bake at ~200 °C after any acid pickling or electroplating to avoid hydrogen embrittlement; shot peening markedly improves fatigue life.
Can A229 be formed, bent or molded?
Coil cold on standard spring machines (Class I coils easier than Class II), then stress relieve 230–290 °C for 20–30 min; keep bend radii generous and avoid sharp hook transitions.
What is the maximum service temperature of A229?
A229 is rated for continuous use to about 150°C (302 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A229-CL1 and A229-CL2?
CL1 is the default condition — default economy oil-tempered wire for static and lightly cycled springs; widest diameter availability and lowest price. CL2: pick when higher stress or smaller spring envelope is needed; ~10 % higher tensile than Class I at the cost of coilability. Yield strength is 1,320 MPa in CL1 versus 1,450 MPa in CL2.
How much does A229 cost?
A229 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
- ASTM A229/A229M — Steel Wire, Quenched and Tempered for Mechanical Springs — ASTM International (2017)
- JIS G 3560 — Oil tempered carbon steel wire (SWO-A / SWO-B) — JSA (2018)
- Handbook of Spring Design — Spring Manufacturers Institute (SMI) (2013)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Oil-tempered spring wire product data — Suzuki Garphytten / Kiswire (typical mill data) (2022)
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.