Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
A286 Round Bar
A286 round bar is the canonical raw stock for A286 fastener, machined-component, and precision-machinery production. TorqBolt manufactures A286 round bar to AMS 5737 (the highest-volume bar specification), AMS 5731 (solution-treated), AMS 5732 (sol-treated and aged), AMS 5734 / 5736, ASTM A453 grade 660 (Class A/B/C/D), ASTM A638 grade 660 (Type 1/2), and ASTM B637 standards. Sizes 5-200 mm / 1/4 inch to 8 inch in hot-rolled, cold-drawn, peeled, and ground finishes. Heat-treated to deliver 130 ksi (895 MPa) tensile, 95 ksi (655 MPa) yield, retained mechanical properties from -196 °C cryogenic to 700 °C continuous service. See parent A286 bar stock, sister variants A286 hex bar, square bar, flat bar, forged bar, and the canonical chemical composition + A286 mechanical-property data + heat treatment.
About A286 Round Bar
A286 round bar production starts with VIM-VAR (vacuum-induction-melted + vacuum-arc-remelted) ingot, the aerospace industry standard for premium-quality A286. Ingot is broken down at 1095 °C through cogging, then hot-rolled or extruded to intermediate diameters, and cold-drawn or peeled to final dimension. AMS 5737 is the most-cited bar spec, covering precision sol-treated and aged round bar in a controlled hardness window (29-32 HRC). AMS 5731 covers sol-treated only (downstream user performs aging). AMS 5732 covers sol-treated and aged from the mill. Each round bar lot is heat-treated per the applicable spec, surface-finished by pickling or grinding, and ships with EN 10204 3.1 mill cert (3.2 third-party-witness available). Bar OD tolerance: ±0.05 mm cold-drawn, ±0.10 mm hot-rolled, ±0.025 mm ground precision.
A286 Round Bar Production Conditions & Standards
TorqBolt produces A286 round bar in five primary production conditions:
- Hot-rolled annealed (AMS 5731), Hot-rolled to size, then solution-treated 1800 °F (982 °C) and quenched. Bar hardness 24-28 HRC. Used as raw stock for downstream aging by the customer.
- Hot-rolled solution-treated and aged (AMS 5732), Hot-rolled, sol-treated 1650 °F (899 °C), aged 1325 °F (718 °C) × 16 h. Hardness 29-32 HRC. The default mill-aged condition for fastener manufacture.
- Cold-drawn precision aged (AMS 5737), Cold-drawn to tighter ⌀ tolerance (±0.05 mm), sol-treated and aged. Hardness 30-34 HRC. Used for precision machined parts and cold-headed fasteners.
- Peeled / centerless-ground (precision), Cold-drawn bar peeled to remove surface oxide, then centerless-ground to ±0.025 mm tolerance. Surface roughness Ra ≤ 0.4 µm. Used for shaft applications and aerospace precision parts.
- Wrought + ASTM B637, Solution-treated bar per ASTM B637, the equivalent of AMS 5731 used for precipitation-hardenable bar in non-aerospace high-temperature service.
A286 Round Bar Sizes & Tolerances
| Diameter | Hot-rolled tol. (AMS 5731) | Cold-drawn tol. (AMS 5737) | Peeled / ground tol. | Available conditions |
|---|---|---|---|---|
| 5-12 mm (1/4-1/2 inch) | +0.30 / -0.10 mm | +0.05 / -0.05 mm | ±0.025 mm | AMS 5731 / 5732 / 5737 / B637 |
| 13-20 mm (1/2-3/4 inch) | +0.40 / -0.10 mm | +0.07 / -0.07 mm | ±0.025 mm | AMS 5731 / 5732 / 5737 / B637 |
| 21-30 mm (3/4-1-1/4 inch) | +0.50 / -0.10 mm | +0.10 / -0.10 mm | ±0.025 mm | AMS 5731 / 5732 / 5737 / B637 |
| 31-50 mm (1-1/4-2 inch) | +0.60 / -0.10 mm | +0.13 / -0.13 mm | ±0.05 mm | AMS 5731 / 5732 / B637 |
| 51-100 mm (2-4 inch) | +0.80 / -0.10 mm | +0.15 / -0.15 mm | ±0.05 mm | AMS 5731 / 5732 / B637 |
| 101-150 mm (4-6 inch) | +1.20 / -0.20 mm | ±0.10 mm | AMS 5731 / B637 | |
| 151-200 mm (6-8 inch) | +1.50 / -0.20 mm | ±0.13 mm | AMS 5731 / 5734 / B637 |
A286 Round Bar Manufacturing Process
Every a286 round bar TorqBolt ships traces back to a vacuum-induction-melted plus vacuum-arc-remelted (VIM-VAR) ingot meeting AMS 5731 / 5732 chemistry. The complete process route:
- VIM-VAR ingot: Vacuum-induction-melted + vacuum-arc-remelted ingot to AMS 5731 / 5732 chemistry. Element ranges per ASTM A453 grade 660. AS9100D for aerospace lots.
- Cogging: Ingot broken down at 1095 °C through hammer or press cogging, reduces ingot to intermediate billet diameter (typically 200-300 mm).
- Hot rolling / extrusion: Billet hot-rolled to bar diameter through a roll mill (sizes 25-200 mm) or extruded (smaller sizes). Process temperatures 1095-1150 °C; finish temp ≥ 925 °C to prevent grain coarsening.
- Pickling / cleaning: Hot-rolled bar pickled in HNO₃ + HF to remove mill scale. Surface inspected for laps, seams per ASTM E45.
- Cold drawing (sizes ≤ 50 mm): Hot-rolled bar cold-drawn through a die, single or multi-pass, to final OD with ±0.05 mm tolerance. Cold drawing also work-hardens the surface for improved machinability.
- Peeling / centerless grinding (precision): Cold-drawn bar peeled to remove surface defects, then centerless-ground for tighter tolerance (±0.025 mm) and lower surface roughness (Ra ≤ 0.4 µm).
- Solution treatment: Vacuum or atmosphere-controlled furnace at 1650 °F (899 °C, AMS 5737) or 1800 °F (982 °C, AMS 5731 / 5732). 1 hour per inch of section, oil-quench.
- Precipitation aging: 1325 °F (718 °C) for 16 hours, air-cool. Develops gamma-prime Ni₃(Ti,Al). Hardness 277-302 HBW for AMS 5732 / 5737.
- Inspection + cut to length: Bar dimensionally inspected (OD, straightness, length), cut to drawing length on band saw or abrasive cut-off. Heat-traceability label on each bar.
A286 Round Bar Inspection & Certification
Each lot ships with a signed inspection certificate. Aerospace orders default to AS9100D first-article reporting per AS9102. Industrial orders default to EN 10204 type 3.1; sour-service and offshore step up to type 3.2 with third-party witness. Inspection scope:
- OD dimensional check by ring gauge or laser micrometer per AMS 5737 tolerance.
- Straightness check per ASTM A484, typical 1-2 mm/m for cold-drawn, 3-4 mm/m for hot-rolled.
- Surface inspection per ASTM E45 inclusion rating + 100 % visual for laps, seams, cracks.
- Hardness sample 1 per heat per ASTM E384, 4-point Vickers on cross-section.
- Tensile coupon from each heat per ASTM E8 + elevated-temperature per E21.
- Macrostructure check, etch a transverse slice from each heat and inspect grain flow per ASTM E381.
- Magnetic permeability < 1.005 per ASTM A342 on every aerospace heat.
- AS9102 first-article on aerospace heats; EN 10204 3.1 commercial heats with heat-traceability label.
A286 Round Bar Downstream Forming & Machining
Round bar is raw stock, torque does not apply directly. Downstream machining and forming operations: cold heading typically requires 100-150 % of yield force on the bar cross-section to upset the head; thread rolling requires 1.5-2 × yield. For machining, cutting forces follow recommended A286 machinability parameters: 30-40 m/min cutting speed, 0.10-0.15 mm/rev feed for carbide tooling. Aging shrinkage is ~0.05 % linear, design machining allowance accordingly. Bar straightness is critical for aerospace shaft applications: spec ≤ 1 mm/m for centerless-ground, ≤ 2 mm/m for cold-drawn.
A286 Round Bar Applications by Industry & End Product
A286 round bar feeds downstream fastener and machined-component production:
- Aerospace fastener production: Cold-drawn AMS 5737 round bar feeds A286 hex bolts, SHCS, NAS bolts manufacture. A286 jet engine fasteners.
- Industrial gas turbine shafting: Hot-rolled AMS 5731 / 5732 large-diameter round bar (M40-M150) for turbine compressor shafts, accessory drive shafts, generator coupling shafts.
- Aerospace machined components: Peeled / ground round bar for engine accessory housings, fuel-system bodies, hydraulic actuator pistons.
- Cryogenic LNG / hydrogen valve bodies: AMS 5732 round bar for LNG valve internals, hydrogen storage manifold bodies, A286 retains 85 % of room-temperature toughness at -196 °C.
- Nuclear reactor internal shafting: ASTM A453 grade 660 round bar for ASME III pressure-vessel internals, control-rod-drive shaft components. A286 nuclear applications.
- Oil & gas downhole tool bodies: ASTM B637 round bar for downhole-tool body machining, NACE MR0175 sour-service when hardness ≤ HRC 35 verified.
Governing Standards & Material Specifications
Every A286 bar product is released against the applicable industry standard. EN 10204 type 3.1 mill certificates ship with every order. See the consolidated A286 AMS / ASTM specifications hub for full spec scope.
| Authority | Specification | Coverage |
|---|---|---|
| ASTM | A453 grade 660 Cl. A/B/C/D | High-temperature bolting material |
| ASTM | A638 grade 660 Type 1/2 | Forged bolting stock |
| ASTM | B637 | Precipitation-hardenable bar |
| AMS | 5731 | Bar / forging, solution-treated |
| AMS | 5732 | Bar / forging, solution-treated and aged |
| AMS | 5737 | Bar, sol-treated and aged (precision) |
| UNS | S66286 | Material designation |
| DIN | 1.4980 / X5NiCrTiMoVB25-15-2 | European designation |
| EN | 10204 3.1 / 3.2 | Mill / third-party-witness certification |
A286 Round Bar vs Alternative Materials
Engineers compare A286 bar against three alternatives: A286 vs Inconel 718, A286 vs 17-4 PH, and A286 vs Waspaloy. See A286 equivalent grades.
How to Specify A286 Round Bar
A complete a286 round bar callout should include: material spec, heat-treatment condition, dimensional standard, size, surface finish, marking, inspection certificate. Example callout:
A286 round bar, AMS 5737, ASTM A453 grade 660 Class A, sol-treated and aged, ⌀ 25.4 mm (1.0 inch), length 3000 mm, cold-drawn finish, ±0.05 mm OD tolerance, straightness ≤ 2 mm/m, EN 10204 3.1, heat-traceability label.
A286 Round Bar, Frequently Asked Questions
What is the most common AMS spec for A286 round bar?
AMS 5737, solution-treated and precipitation-aged bar, the highest-volume bar specification. Used on aerospace bolt and SHCS production. AMS 5732 covers similar properties but with the alternative 1650 °F + aged or 1800 °F + aged solution treatment per drawing.
What's the difference between hot-rolled and cold-drawn A286 bar?
Hot-rolled: rolled at 1095-1150 °C, surface oxide removed by pickling, OD tolerance ±0.10-1.5 mm depending on size. Cold-drawn: hot-rolled bar drawn cold through a die to tighter OD tolerance (±0.05-0.15 mm) and improved surface finish. Cold-drawn is required for precision fastener and machined-component manufacture.
What is the maximum diameter of A286 round bar?
Standard production: 200 mm (8 inch). Custom-drawing: up to 300 mm (12 inch) in hot-rolled or forged condition. For larger diameters use A286 forged bar.
Can A286 round bar be supplied in cryogenic-tested condition?
Yes. A286 retains 85 % of room-temperature toughness at -196 °C. Charpy V-notch testing per ASTM E23 at -196 °C available with EN 10204 3.2 third-party-witness certification for safety-critical cryogenic LNG and hydrogen-storage applications.
Is A286 round bar magnetic?
No. The austenitic FCC matrix has magnetic permeability < 1.005 verified per ASTM A342, preserved through cold drawing, sol-treatment, and aging. Critical for instrumentation and aerospace electromagnetic-sensitive shafting applications.
What surface finish on A286 round bar?
Hot-rolled: pickled finish, Ra ~6-12 µm. Cold-drawn: surface Ra ~1-3 µm. Peeled: Ra ~1.5-2 µm. Centerless-ground: Ra ≤ 0.4 µm (16 µin). Specify per drawing, finer finish increases cost ~30-50 % per step.
What's the lead time on AMS 5737 cold-drawn round bar?
Standard sizes 5-50 mm: 4-6 weeks from heat release. Larger sizes 50-100 mm: 6-10 weeks. Aerospace lots with AS9102 first-article: add 1-2 weeks.
Can A286 round bar be NACE MR0175 verified?
Yes, when supplied in the appropriate hardness condition (HV ≤ 327 / HRC ≤ 35) per NACE MR0175 / ISO 15156-3 for sour-service applications. Specify on PO; each heat receives Vickers traverse before release.
What's the difference between AMS 5731 and AMS 5732 round bar?
AMS 5731: bar / forging / tubing / rings, solution-treated only, downstream user performs aging. AMS 5732: bar / forging / tubing, solution-treated AND precipitation-aged from the mill, ready for use without further heat treatment. AMS 5732 is the most common mill-aged spec; AMS 5731 is preferred when aging needs to be timed with downstream fabrication.
Why TorqBolt for A286 Round Bar
Three reasons aerospace and gas-turbine OEMs place a286 round bar orders with us:
- Vertically integrated supply, VIM-VAR melt sourcing from approved AMS-conforming mills, in-house hot-rolling + cold-drawing + vacuum heat-treatment. No outsourced critical step.
- Aerospace AQMS, AS9100D-certified factory in Mumbai with published quality manual.
- Lead time discipline, 4-6 weeks for ASTM A453 grade 660 standard sizes, 8-12 weeks for custom-drawing aerospace parts.
Three decades of fastener-manufacturing experience; current certifications: ISO 9001:2015, AS9100D, PED 2014/68/EU, NORSOK M-650 QTR.
Recent A286 Round Bar Order Patterns
TorqBolt's regular A286 round bar order book covers four recurring application categories: cold-drawn AMS 5737 ⌀ 12-25 mm for fastener-maker downstream production, hot-rolled AMS 5731 ⌀ 50-100 mm for industrial gas-turbine shafting, peeled / centerless-ground precision bar ⌀ 6-20 mm for aerospace machined components, and ASTM B637 ⌀ 30-75 mm for oil & gas downhole tool bodies.
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