Steel A227 CLII
Grade
ASTM A227
CLII = class II
Choose when a higher stress level or smaller spring index is required; tensile is roughly 10 % above Class I at the same diameter, with slightly less ductility for coiling.
Values for the CLII condition
Other A227 tempers and conditions
A227 is listed in 3 conditions; see the grade overview at A227.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
CLIDefault Class I | Default general-purpose hard-drawn spring wire for moderate-stress static or low-cycle springs where cost matters. | 1,380 | 1,620 | 4 | 46 HRC | — |
Stress relieved | Standard post-coiling low-temperature bake that restores elastic limit, reduces set/relaxation and removes plating hydrogen; use for all finished springs. | 1,480 | 1,650 | 4 | 47 HRC | 9.5 % IACS |
CLIIThis page Class II | Choose when a higher stress level or smaller spring index is required; tensile is roughly 10 % above Class I at the same diameter, with slightly less ductility for coiling. | 1,520 | 1,790 | 3 | 49 HRC | — |
What is A227 CLII?
A227 CLII is A227 in the CLII grade — choose when a higher stress level or smaller spring index is required; tensile is roughly 10 % above Class I at the same diameter, with slightly less ductility for coiling. A227 CLII has a yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,790 MPa (260 ksi) — stronger than 97% of steel grades. Elongation at break is 3% and the elastic modulus is 200 GPa (29 Msi). A227 CLII has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). CLI is the default condition FabDigit quotes; CLII is available on request or by drawing note.
Advantages
- High strength — 1,520 MPa (220 ksi), better than 97% 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 machine — 22/100, worse than 95% of steel grades
- Low fracture toughness — 35 MPa·√m (31.9 ksi·√in), worse than 94% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
A227 CLII properties
Typical room-temperature values for A227 CLII; 13 are specific to this condition. Other listed values are A227 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A227 CLII has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical15
A227 CLII has a yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,790 MPa (260 ksi) — stronger than 97% of steel grades. Elongation at break is 3% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
A227 CLII is rated for continuous service to 120°C (248 °F). It conducts heat at 47 W/m·K (27.2 BTU/hr·ft·°F), better than 75% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
A227 CLII 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 A227 CLII takes about 28 MJ of energy and emits 2.1 kg of CO₂ — less than 56% of steel grades. Typical recycled content is 25%.
Manufacturability7
A227 CLII's machinability is poor (22/100, worse than 95% of steel grades); weldability poor (15/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A227 CLII
Is A227 easy to machine?
Rarely machined — the drawn wire is hard and abrasive; grind, shear, or abrasive-cut ends rather than turn or drill.
Can A227 be welded?
Essentially unweldable in service condition: 0.45–0.85 % C gives a brittle martensitic HAZ; use mechanical hooks/loops or resistance-weld only with a controlled post-weld temper.
Can A227 be formed, bent or molded?
Cold-coiled on CNC spring formers straight from the spool; keep spring index ≥4, then bake 230–290 °C for 20–30 min to relieve coiling stresses and set the free length.
What surface finishes work on A227?
Ship oiled or phosphated for indoor use; for corrosion service use mechanical zinc, hot-dip galvanize, or Zn-Ni plate with a post-plate hydrogen-relief bake at 190–220 °C within 4 h.
A227 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 |
|---|---|---|
| CASTM A227 heat analysis; the Chinese equivalent 65Mn sits at 0.62–0.70 % C | 0.45 – 0.85 | 0.65 |
| Mn65Mn: 0.90–1.20 % | 0.3 – 1.3 | 0.8 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.05 | 0.03 |
| Sitypical for 65Mn / silicon-killed rod; not always specified in A227 | 0.15 – 0.35 | 0.25 |
| Fe | balance | — |
A227 CLII — frequently asked
What is A227 CLII used for?
A227 CLII is typically used for mechanical springs, clips, wire forms and general-purpose coil springs. In short: cheapest general spring wire; cold-coiled as drawn; not fatigue-rated.
What is the yield strength of A227 CLII?
A227 CLII has a typical yield strength of 1,520 MPa (220 ksi) and a tensile strength of 1,790 MPa (260 ksi) — stronger than 97% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is A227 CLII easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of steel grades). Rarely machined — the drawn wire is hard and abrasive; grind, shear, or abrasive-cut ends rather than turn or drill.
Can A227 CLII be welded?
Not readily — weldability is rated poor (15/100). Essentially unweldable in service condition: 0.45–0.85 % C gives a brittle martensitic HAZ; use mechanical hooks/loops or resistance-weld only with a controlled post-weld temper.
What surface finishes work on A227 CLII?
Ship oiled or phosphated for indoor use; for corrosion service use mechanical zinc, hot-dip galvanize, or Zn-Ni plate with a post-plate hydrogen-relief bake at 190–220 °C within 4 h.
Can A227 CLII be formed, bent or molded?
Cold-coiled on CNC spring formers straight from the spool; keep spring index ≥4, then bake 230–290 °C for 20–30 min to relieve coiling stresses and set the free length.
What is the maximum service temperature of A227 CLII?
A227 CLII 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 A227-CLI and A227 CLII?
CLI is the default condition — default general-purpose hard-drawn spring wire for moderate-stress static or low-cycle springs where cost matters. CLII: choose when a higher stress level or smaller spring index is required; tensile is roughly 10 % above Class I at the same diameter, with slightly less ductility for coiling. Yield strength is 1,380 MPa in CLI versus 1,520 MPa in CLII.
Sources
- ASTM A227/A227M — Standard Specification for Steel Wire, Cold-Drawn for Mechanical Springs — ASTM International (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Spring Steels) — ASM International (1990)
- Handbook of Spring Design — Spring Manufacturers Institute (SMI) (2013)
- ASTM A370 — Mechanical Testing of Steel Products (hardness conversions) — ASTM International (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.