Steel 8655
AISI/SAE 8655 · UNS G86550
8655 is a nickel-chromium-molybdenum alloy steel with about 0.55 % C (UNS G86550), sitting at the high-carbon end of the SAE 86xx series and developing its properties by quenching and tempering.
Reference datasheet — 8655 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 A condition
8655 tempers and conditions
8655 is supplied in 11 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Choose for maximum softness/ductility before cold heading, deep machining or severe forming of this high-carbon grade. | 380 | 690 | 25 | 13 HRC | 8 % IACS |
ADefault Solution annealed | Softest condition — the usual bar stock form for machining before hardening. | 400 | 750 | 21 | 223 HB | — |
Hot rolled | Lowest-cost mill form for parts that will be fully heat treated after rough machining. | 520 | 900 | 16 | 26 HRC | 7.8 % IACS |
Normalized | Use to refine grain and homogenize forgings before final quench and temper. | 710 | 1,080 | 13 | 33 HRC | — |
Cold drawn | Pick for tight size tolerance and straight, bright bar with higher as-supplied strength. | 720 | 860 | 10 | 25 HRC | 7.8 % IACS |
Q&T 650 °C | Softest Q&T condition — best ductility and machinability while keeping tempered-martensite structure. | 915 | 1,020 | 19 | 29 HRC | — |
induction hardened and tempered surface | Use when a hard wear surface (55–60 HRC case) is needed over a tougher Q&T core. | 1,080 | 1,250 | 10 | 57 HRC | 7.4 % IACS |
Q&T 540 °C | General-purpose quenched-and-tempered condition where impact toughness matters more than wear. | 1,140 | 1,250 | 15 | 35 HRC | — |
Q&T 425 °C | Balanced strength/toughness for highly stressed shafts, pins and springs. | 1,420 | 1,550 | 12 | 43 HRC | — |
Q&T 315 °C | Very high strength with slightly better toughness than the 205 °C temper; typical for wear plates and dies. | 1,620 | 1,830 | 10 | 50 HRC | — |
Q&T 205 °C | Maximum hardness and wear resistance; use only where impact loading is low. | 1,700 | 2,000 | 9 | 55 HRC | 41 W/m·K |
What is 8655?
8655 is a nickel-chromium-molybdenum alloy steel with about 0.55 % C (UNS G86550), sitting at the high-carbon end of the SAE 86xx series and developing its properties by quenching and tempering. Engineers specify it for high-strength bolts, springs and heavy-duty gears, and it is stocked as hot-rolled, cold-drawn, annealed and spheroidized bar plus forging stock in QT205 through QT650 tempers; the reference condition gives 400 MPa yield, 750 MPa tensile, 21 % elongation and 223 HB with service to 400 °C. The limits are poor weldability (CE ≈ 1.0), low formability (score 30) and only moderate machinability (score 50). Use 4140 where welding or greater ductility is needed. 8655 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). 8655 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 60% of steel grades. Elongation at break is 21% and the elastic modulus is 205 GPa (29.7 Msi).
What is 8655 used for?
- high-strength bolts
- springs
- wear parts
- heavy-duty gears
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to weld — 20/100, worse than 84% of steel grades
8655 properties
Typical room-temperature values for 8655-A; bars are the position among steel grades.
Physical3
8655 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
8655 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 60% of steel grades. Elongation at break is 21% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
8655 is rated for continuous service to 400°C (752 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
8655 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of 8655 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
8655's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (20/100); 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. 8655 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 8655
Is 8655 easy to machine?
Machine in the annealed or spheroidized state with rigid setups and carbide tooling; above ~40 HRC switch to CBN/ceramic or grinding.
Can 8655 be welded?
Poor weldability (CE ≈ 1.0) — preheat 250–350 °C, low-hydrogen consumables and immediate post-weld temper are required; avoid welding on hardened parts.
Can 8655 be formed, bent or molded?
Hot forge 1100–1200 °C and cool slowly to avoid cracking; cold forming limited to gentle bends in the spheroidized condition.
8655 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 |
|---|---|---|
| CSAE J404 / ASTM A29 grade 8655 | 0.5 – 0.6 | 0.55 |
| Mn | 0.75 – 1 | 0.88 |
| Si | 0.15 – 0.35 | 0.25 |
| Ni | 0.4 – 0.7 | 0.55 |
| Cr | 0.4 – 0.6 | 0.5 |
| Mo | 0.15 – 0.25 | 0.2 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Fe | balance |
What surface finishes work on 8655?
No anodizing; protect with black oxide, phosphate-and-oil, zinc or hard chrome, and bake after plating to avoid hydrogen embrittlement at high hardness.
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 8655 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G86550
How much does 8655 cost?
8655 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.
8655 — frequently asked
What is 8655 used for?
8655 is typically used for high-strength bolts, springs, wear parts and heavy-duty gears. In short: highest-carbon 86xx grade; through-hardening wear steel; poor weldability, hot-form only.
What is the yield strength of 8655?
8655 has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 750 MPa (109 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is 8655 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the annealed or spheroidized state with rigid setups and carbide tooling; above ~40 HRC switch to CBN/ceramic or grinding.
Can 8655 be welded?
Not readily — weldability is rated poor (20/100). Poor weldability (CE ≈ 1.0) — preheat 250–350 °C, low-hydrogen consumables and immediate post-weld temper are required; avoid welding on hardened parts.
What surface finishes work on 8655?
No anodizing; protect with black oxide, phosphate-and-oil, zinc or hard chrome, and bake after plating to avoid hydrogen embrittlement at high hardness.
Can 8655 be formed, bent or molded?
Hot forge 1100–1200 °C and cool slowly to avoid cracking; cold forming limited to gentle bends in the spheroidized condition.
What is the maximum service temperature of 8655?
8655 is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 8655-A and 8655-QT205?
A is the default condition — softest condition — the usual bar stock form for machining before hardening. QT205: maximum hardness and wear resistance; use only where impact loading is low. Yield strength is 400 MPa in A versus 1,700 MPa in QT205.
How much does 8655 cost?
8655 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
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- ASTM A29/A29M — Steel Bars, Carbon and Alloy, Hot-Wrought — ASTM (2020)
- SAE J1268 — Hardenability Bands for Carbon and Alloy H Steels — SAE International (2019)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating — ASM International (1991)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
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.