Steel 85
AISI/SAE 1084
85 is a plain high-carbon spring steel at about 0.85 % C, close to AISI 1084, offering a higher attainable hardness than grade 70 in thin sections.
Reference datasheet — 85 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 QT condition
85 tempers and conditions
85 is supplied in 12 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 12 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition for blanking, machining and cold forming of strip and bar before hardening. | 400 | 690 | 22 | 192 HB | — |
Hot rolled | Mill supply condition for bar and hot-rolled strip; must be annealed before machining and quenched before use. | 550 | 950 | 12 | 29 HRC | 10 % IACS |
Normalized | Grain-refining pre-treatment for forged or heavily worked stock before hardening. | 590 | 1,010 | 11 | 31 HRC | 10 % IACS |
Cold drawn | Bright bar/wire with close tolerance for machined spring parts hardened afterwards. | 700 | 850 | 9 | 24 HRC | 10.5 % IACS |
QTDefault Quenched and tempered | Standard reference spring temper: good balance of elastic limit and toughness for general flat and coil springs. | 1,080 | 1,230 | 8 | 40 HRC | — |
Cold rolled hard strip | Work-hardened thin strip used directly for light shims/clips or as blanking stock for later hardening. | 1,100 | 1,250 | 3 | 40 HRC | 9.5 % IACS |
quenched + tempered ~400 °C | Higher elastic limit for thin flat springs, clips and washers where deflection loads are high. | 1,400 | 1,550 | 5 | 46 HRC | — |
Blue tempered / scaleless hardened-and-tempered spring strip | Ready-to-use hardened strip with blue oxide finish — buy this for stamped flat springs with no in-house heat treatment. | 1,450 | 1,600 | 4 | 47 HRC | 9 % IACS |
Oil quenched and tempered spring wire | Uniform tempered-martensite wire for coil springs needing consistent relaxation resistance without post-coiling hardening. | 1,450 | 1,650 | 6 | 48 HRC | 9.2 % IACS |
Patented (lead-bath) cold drawn spring wire | Fine-pearlite drawn wire for cold-coiled small springs; strength rises sharply as diameter falls. | 1,550 | 1,800 | 3 | 48 HRC | 9.2 % IACS |
quenched + low tempered 200–300 °C | Blade-like spring parts, scrapers, doctor blades and cutting-edge components needing wear resistance. | 1,650 | 1,850 | 3 | 53 HRC | — |
As-quenched | Intermediate condition only — maximum hardness but brittle; must be tempered immediately. | 1,900 | 2,200 | 0.5 | 64 HRC | 7.2 % IACS |
What is 85?
85 is a plain high-carbon spring steel at about 0.85 % C, close to AISI 1084, offering a higher attainable hardness than grade 70 in thin sections. In the tempered condition on file it runs about 1080 MPa yield, 1230 MPa tensile, 375 HB / 40 HRC with 8 % elongation, and harder QT-45-48 HRC and QT-50-55 HRC tempers plus annealed, cold-drawn, cold-rolled-hard, patented-drawn and oil-tempered conditions are also listed. It is used for thin flat springs and blade-like spring parts. Hardenability is shallow, corrosion resistance is nil and service is capped near 250 °C; for thicker sections use an alloyed grade such as 61SiCrV6. 85 has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,400°C (2,552 °F). 85 has a yield strength of 1,080 MPa (157 ksi) and a tensile strength of 1,230 MPa (178 ksi) — stronger than 93% of steel grades. Elongation at break is 8% and the elastic modulus is 207 GPa (30 Msi).
What is 85 used for?
- Flat springs
- Blade springs
- Small die springs
Advantages
- High strength — 1,080 MPa (157 ksi), better than 93% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
Limitations
- Limited ductility — 8%, worse than 95% of steel grades
- Low fracture toughness — 40 MPa·√m (36.4 ksi·√in), worse than 92% of steel grades
- Limited formability — 12/100, worse than 92% of steel grades
- Difficult to weld — 15/100, worse than 91% of steel grades
- Difficult to machine — 30/100, worse than 89% of steel grades
85 properties
Typical room-temperature values for 85-QT; bars are the position among steel grades.
Physical3
85 has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical16
85 has a yield strength of 1,080 MPa (157 ksi) and a tensile strength of 1,230 MPa (178 ksi) — stronger than 93% of steel grades. Elongation at break is 8% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
85 is rated for continuous service to 250°C (482 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
85 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 85 takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability6
85's machinability is poor (30/100, worse than 89% of steel grades); weldability poor (15/100); formability not recommended (12/100).
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. 85 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 85
Is 85 easy to machine?
Machine only in the spheroidize-annealed state (~190 HB) with sharp carbide or HSS tooling; above 45 HRC use grinding or EDM.
Can 85 be welded?
Essentially unweldable in service condition — 0.85 %C gives hard, crack-prone HAZ; if unavoidable preheat 250–350 °C and temper immediately after.
Can 85 be formed, bent or molded?
Blank and form in the annealed or cold-rolled state, then harden at 780–820 °C and quench in oil (thin sections) or brine; hardenability is shallow, so keep sections under ~6 mm.
85 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 |
|---|---|---|
| CGB/T 1222 grade 85; AISI 1084 is 0.80–0.93 | 0.82 – 0.9 | 0.86 |
| Si | 0.17 – 0.37 | 0.27 |
| Mn | 0.5 – 0.8 | 0.65 |
| Crresidual | ≤ 0.25 | |
| Niresidual | ≤ 0.35 | |
| Curesidual | ≤ 0.25 | |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Fe | balance |
What surface finishes work on 85?
Bare surface rusts quickly — finish with black-oxide/blueing plus oil, phosphate, zinc or nickel plate; bake after plating at 190–200 °C to avoid hydrogen embrittlement.
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 85 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- AISI / SAE
- 1084
How much does 85 cost?
85 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.
85 — frequently asked
What is 85 used for?
85 is typically used for flat springs, blade springs and small die springs. In short: higher hardness than grade 70; thin-section spring strip; shallow hardenability.
What is the yield strength of 85?
85 has a typical yield strength of 1,080 MPa (157 ksi) and a tensile strength of 1,230 MPa (178 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is 85 easy to machine?
Not especially — machinability is rated poor (30/100, worse than 89% of steel grades). Machine only in the spheroidize-annealed state (~190 HB) with sharp carbide or HSS tooling; above 45 HRC use grinding or EDM.
Can 85 be welded?
Not readily — weldability is rated poor (15/100). Essentially unweldable in service condition — 0.85 %C gives hard, crack-prone HAZ; if unavoidable preheat 250–350 °C and temper immediately after.
What surface finishes work on 85?
Bare surface rusts quickly — finish with black-oxide/blueing plus oil, phosphate, zinc or nickel plate; bake after plating at 190–200 °C to avoid hydrogen embrittlement.
Can 85 be formed, bent or molded?
Blank and form in the annealed or cold-rolled state, then harden at 780–820 °C and quench in oil (thin sections) or brine; hardenability is shallow, so keep sections under ~6 mm.
What is the maximum service temperature of 85?
85 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 85-QT and 85-Q?
QT is the default condition — standard reference spring temper: good balance of elastic limit and toughness for general flat and coil springs. Q: intermediate condition only — maximum hardness but brittle; must be tempered immediately. Yield strength is 1,080 MPa in QT versus 1,900 MPa in Q.
How much does 85 cost?
85 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
- GB/T 1222 (2016)
- ASTM A684 / SAE J403 (1084, 1085 carbon steel) — ASTM / SAE (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook (machinability ratings, heat treatment of carbon steels) — Industrial Press (2020)
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.