Steel 1064-OT
Heat-treated state
AISI/SAE 1064 · UNS G10640
OT = oil hardened and tempered spring wire
Uniform tempered-martensite wire for coiled compression/extension springs that must be wound and used without further heat treatment.
Values for the OT condition
Other 1064 tempers and conditions
1064 is listed in 10 conditions; see the grade overview at 1064.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — pick it for maximum machinability and cold-heading/upsetting before hardening. | 340 | 620 | 20 | 174 HB | — |
HRDefault Hot rolled | Cheapest as-supplied bar/rod condition; used when the part will be re-heat-treated or machined lightly. | 370 | 670 | 12 | 197 HB | — |
Normalized | Choose for a uniform fine pearlitic structure and higher strength before machining or induction hardening. | 490 | 815 | 12 | 235 HB | — |
Spheroidize annealed and cold drawn | Best combination for cold-formed / cold-headed high-carbon parts: soft spheroidal carbides with cold-drawn strength and finish. | 490 | 640 | 12 | 187 HB | 9.5 % IACS |
Cold drawn | Standard cold-finished bar with tighter tolerance, bright surface and raised yield strength. | 620 | 720 | 10 | 210 HB | — |
Q&T 540 °C | Tougher structural temper for shafts and machined parts where impact matters more than hardness. | 745 | 965 | 16 | 30 HRC | — |
Q&T 425 °C | Typical spring/high-strength temper: near-peak elastic limit with usable toughness. | 930 | 1,200 | 12 | 38 HRC | — |
Q&T 205 °C | Maximum hardness/wear resistance for blades, small springs and wear parts in thin sections; very low toughness. | 1,140 | 1,590 | 9 | 48 HRC | — |
OTThis page Oil hardened and tempered spring wire | Uniform tempered-martensite wire for coiled compression/extension springs that must be wound and used without further heat treatment. | 1,330 | 1,500 | 8 | 45 HRC | — |
Patented and hard cold drawn spring wire | Highest-strength wire form: lead/air patented then heavily drawn for static springs, rope wire and mattress wire. | 1,400 | 1,600 | 4 | 45 HRC | — |
What is 1064-OT?
1064-OT is 1064 heat treated to OT — uniform tempered-martensite wire for coiled compression/extension springs that must be wound and used without further heat treatment. 1064-OT has a yield strength of 1,330 MPa (193 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 95% of steel grades. Elongation at break is 8% and the elastic modulus is 205 GPa (29.7 Msi). 1064-OT 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). HR is the default condition FabDigit quotes; OT is available on request or by drawing note.
Advantages
- High strength — 1,330 MPa (193 ksi), better than 95% of steel grades
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
Limitations
- Limited service temperature — 150°C (302 °F), worse than 99% of steel grades
- Difficult to machine — 12/100, worse than 99% of steel grades
- Limited ductility — 8%, worse than 95% of steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
- Difficult to weld — 20/100, worse than 84% of steel grades
1064-OT properties
Typical room-temperature values for 1064-OT; 10 are specific to this condition. Other listed values are 1064 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
1064-OT 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).
Mechanical16
1064-OT has a yield strength of 1,330 MPa (193 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 95% of steel grades. Elongation at break is 8% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
1064-OT is rated for continuous service to 150°C (302 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 11.3 µm/m·K (6.28 µin/in·°F).
Electrical3
1064-OT conducts electricity at 9.5 % IACS, better than 75% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of 1064-OT takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
1064-OT's machinability is not recommended (12/100, worse than 99% of steel grades); weldability poor (20/100); formability poor (20/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 1064-OT
Is 1064 easy to machine?
Machine in the spheroidize-annealed condition (≈60 % of 1212); use rigid setups, positive rake carbide and good coolant — hot-rolled pearlite is gummy and hardened stock generally needs grinding.
Can 1064 be welded?
Poor weldability (CE ≈ 0.8): preheat 260–320 °C, use low-hydrogen consumables, control interpass and post-weld temper immediately to avoid untempered martensite and cracking.
Can 1064 be formed, bent or molded?
Cold-form only from spheroidized stock with generous bend radii (≥3t); hot form at 1100–1200 °C and cool slowly, then normalize or anneal before hardening.
What surface finishes work on 1064?
No corrosion resistance — protect with oil, phosphate, black oxide, zinc or zinc-nickel plating; bake at 190–200 °C after plating of high-strength parts to relieve hydrogen embrittlement; polishes and grinds well when hardened.
1064 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, SAE J403 | 0.6 – 0.7 | 0.65 |
| Mn | 0.5 – 0.8 | 0.65 |
| Pmax for merchant quality bar | ≤ 0.04 | 0.02 |
| Smax for merchant quality bar | ≤ 0.05 | 0.03 |
| Sitypical for killed steel; not in SAE J403 base spec | 0.1 – 0.35 | 0.22 |
| Fe | balance | — |
1064-OT — frequently asked
What is 1064-OT used for?
1064-OT is typically used for high-tensile wire, springs, cutlery and wear-resistant parts. In short: spring-wire high-carbon steel; hardest grade in family; very limited weldability.
What is the yield strength of 1064-OT?
1064-OT has a typical yield strength of 1,330 MPa (193 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 95% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is 1064-OT easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 99% of steel grades). Machine in the spheroidize-annealed condition (≈60 % of 1212); use rigid setups, positive rake carbide and good coolant — hot-rolled pearlite is gummy and hardened stock generally needs grinding.
Can 1064-OT be welded?
Not readily — weldability is rated poor (20/100). Poor weldability (CE ≈ 0.8): preheat 260–320 °C, use low-hydrogen consumables, control interpass and post-weld temper immediately to avoid untempered martensite and cracking.
What surface finishes work on 1064-OT?
No corrosion resistance — protect with oil, phosphate, black oxide, zinc or zinc-nickel plating; bake at 190–200 °C after plating of high-strength parts to relieve hydrogen embrittlement; polishes and grinds well when hardened.
Can 1064-OT be formed, bent or molded?
Cold-form only from spheroidized stock with generous bend radii (≥3t); hot form at 1100–1200 °C and cool slowly, then normalize or anneal before hardening.
What is the maximum service temperature of 1064-OT?
1064-OT 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 1064-HR and 1064-PCD?
HR is the default condition — cheapest as-supplied bar/rod condition; used when the part will be re-heat-treated or machined lightly. PCD: highest-strength wire form: lead/air patented then heavily drawn for static springs, rope wire and mattress wire. Yield strength is 370 MPa in HR versus 1,400 MPa in PCD.
Sources
- SAE J403 — Chemical Compositions of SAE Carbon Steels — SAE International (2014)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements — ASTM (2020)
- ASTM A227/A229 — Cold-Drawn and Oil-Tempered Carbon Steel Spring Wire — ASTM (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
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.