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 Metric Bolts
A286 metric bolts are the European / Asian / Indian-spec precision-hardening superalloy fasteners — manufactured by TorqBolt to DIN 931 (partial thread hex), DIN 933 (full thread hex), ISO 4014 / 4017 (international metric hex), ISO 4762 / DIN 912 (socket head), and ISO 7380 / DIN 7380 (button head) standards. Sizes M5-M64 in coarse and fine thread pitch with 6g tolerance per ISO 1502 (commercial) or 4g6g (aerospace). Heat-treated to ASTM A453 grade 660 Class A from AMS 5731 / 5732 bar — 895 MPa tensile, 655 MPa yield, retained preload to 700 °C. Metric bolts dominate European aerospace (Airbus), Japanese auto (turbocharger), Indian power, and most non-US industrial gas-turbine applications. See parent A286 bolts, sister variants A286 hex bolts, A286 metric screws, CRES bolts, and the canonical A286 chemical composition, heat treatment.
About A286 Metric Bolts
Metric A286 bolts cover the M5-M64 size range across all common head and drive types — hex external, hex socket internal, button head, flat head, flange head, and 12-point. Metric is the dominant aerospace standard in Europe (Airbus) and the dominant industrial standard in India, China, Japan, and most non-US markets. TorqBolt manufactures metric A286 bolts to ISO 4014 / 4017 / 4762 dimensional standards with 6g commercial thread tolerance or 4g6g aerospace tolerance per MIL-S-8879 equivalent. Threads are rolled (not cut) post-aging for 30-40 % higher fatigue performance vs cut threads. Each metric bolt is forged from A286 bar per AMS 5731 / 5732, solution-treated 1650 °F, aged 1325 °F × 16 hours, passivated per ASTM A967, head-stamped 'A286' + lot + 'TB'.
A286 Metric Bolt Head Patterns & ISO Standards
TorqBolt produces metric A286 bolts in seven primary head/drive configurations:
- Hex head (DIN 931 partial / 933 full / ISO 4014 / 4017) — External six-flat hex — wrench-across-flats per ISO 272. The most common metric A286 bolt head; M5-M64 sizes.
- Heavy hex (ASME B18.2.1 metric series) — Thicker hex head than DIN 931 — used for high-preload structural bolting where head shear margin matters.
- Hex flange (DIN 6921 / ISO 4162) — Integral flange under head spreads bearing pressure — eliminates separate washer. Common on automotive turbocharger and exhaust-manifold bolting.
- Socket head cap (ISO 4762 / DIN 912) — Cylindrical head, internal hex (Allen) drive — for compact joints with limited wrench clearance. M3-M48 sizes.
- Button head socket (ISO 7380 / DIN 7380) — Low-profile dome head with hex socket — decorative or low-clearance applications. M3-M16.
- Flat (countersunk) head socket (ISO 10642 / DIN 7991) — 90° countersunk head with hex socket — flush-mount applications. M3-M30.
- 12-point flange (DIN 6932 / IFI-115) — Bi-hex external drive metric variant — high-torque aerospace and motorsport applications. Less common than NAS 6603 inch.
A286 Metric Bolt Sizes & Specifications
| Metric size | Coarse pitch | Fine pitch | Wrench AF (DIN 931) | Hex socket (ISO 4762) | Tensile area mm² | Min. tensile (kN) |
|---|---|---|---|---|---|---|
| M5 | 0.8 | — | 8 mm | 4 mm | 14.2 | 12.7 |
| M6 | 1.0 | — | 10 mm | 5 mm | 20.1 | 18.0 |
| M8 | 1.25 | 1.0 | 13 mm | 6 mm | 36.6 | 32.7 |
| M10 | 1.5 | 1.25 | 17 mm | 8 mm | 58.0 | 51.9 |
| M12 | 1.75 | 1.25 | 19 mm | 10 mm | 84.3 | 75.5 |
| M16 | 2.0 | 1.5 | 24 mm | 14 mm | 157 | 140 |
| M20 | 2.5 | 1.5 | 30 mm | 17 mm | 245 | 219 |
| M24 | 3.0 | 2.0 | 36 mm | — | 353 | 316 |
| M30 | 3.5 | 2.0 | 46 mm | — | 561 | 502 |
| M36 | 4.0 | 3.0 | 55 mm | — | 817 | 731 |
| M48 | 5.0 | 3.0 | 75 mm | — | 1473 | 1318 |
A286 Metric Bolts Manufacturing Process
Every a286 metric bolts 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 melt: Bar to AMS 5731 / 5732 chemistry per ASTM A453 grade 660. ISO 9001 + AS9100D for aerospace lots.
- Bar production: Hot-rolled or cold-drawn to ISO 4014 starting blank. Fine-pitch threads use cold-drawn bar for dimensional precision.
- Cold heading (sizes ≤ M16): Multi-station bolt-maker forms hex head + cone + extrusion in one cycle per ISO 4014 dimensions.
- Hot heading (sizes ≥ M18): Heated to 1050 °C, upset in hex die-press for M18-M64 ranges where cold-heading force is impractical.
- Thread rolling 6g: Cylindrical or flat-die thread rolling to ISO 1502 6g tolerance (commercial) or 4g6g (aerospace MIL-S-8879 equivalent).
- Solution treatment: Vacuum heat-treat 1650 °F (899 °C) per AMS 5737 / ASTM A453 Class A; or 1800 °F (982 °C) per AMS 5732 / Class B. 1 hour per inch, oil-quench.
- Precipitation aging: 1325 °F (718 °C) for 16 hours, air-cool. Develops Ni₃(Ti,Al) gamma-prime. Hardness 29-32 HRC.
- Passivation per ASTM A967: Pickle + HNO₃ rinse + passivate. Optional silver / nickel anti-galling coat for above-540 °C service.
- Marking + pack: Head-stamped 'A286' + grade 'GR 660' (per ASTM F788) + lot + manufacturer 'TB'. Bulk pack 100 / 250 / 500 pcs depending on size.
A286 Metric Bolts 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.
- 100 % thread-gauge GO/NO-GO per ISO 1502 (commercial) or MIL-S-8879 (aerospace).
- Wrench across-flats dimension verified by snap gauge (typ. ±0.30 mm at M16).
- Hardness traverse 4-point Vickers per ASTM E384 on each heat-treat batch.
- Magnetic permeability < 1.005 per ASTM A342 on every aerospace coil.
- Tensile coupon from each heat — yield, tensile, elongation, RA per ISO 6892-1.
- LPI per ASTM E1417 / ISO 3452 on every aerospace lot.
- Salt-spray ASTM B117 96-hour for passivated lots.
- AS9102 first-article on aerospace lots; EN 10204 3.1 mill cert standard for industrial lots.
A286 Metric Bolts Torque & Assembly Practice
Metric A286 bolts pre-stress to 75 % of room-temperature 0.2 % yield (~ 490 MPa residual stress for grade 660 Class A). Common torque values M16 oil-lubricated 280 N·m / anti-seize 180 N·m; M24 980 N·m / 620 N·m; M30 1900 N·m / 1200 N·m. Above 540 °C apply nickel or copper anti-seize per AS5272 to threads — austenitic-stainless threads gall above this temperature. ISO standards for high-temperature bolted joints (ISO 16047 friction coefficient testing, EN 1591 flange calculation) define preload retention vs temperature. For ASME-spec joints, US torque tables in MIL-HDBK-60 take precedence over ISO.
A286 Metric Bolt Applications by Industry
Metric A286 bolts dominate non-US aerospace and industrial applications:
- European aerospace (Airbus): A286 metric bolts on Airbus A320 / A330 / A350 engine pylons, fuselage frames, and structural attach points. ISO 4014 hex bolts and ISO 4762 SHCS the standard.
- Industrial gas turbines (Siemens / MAN): Siemens SGT-800 / SGT-A65 and MAN MGT-6000 use M16-M30 metric A286 hex bolts on casing-split flange. A286 gas turbine applications.
- Asian aerospace (HAL / Kawasaki / KAI): HAL Tejas, Mitsubishi MRJ, KAI T-50 use metric A286 hex and SHCS on engine and structure attach.
- Automotive turbocharger: M6-M12 hex flange bolts (DIN 6921) on Garrett, BorgWarner, IHI turbocharger waste-gates and manifolds. 600-700 °C cyclic.
- Indian power generation: BHEL gas-turbine and steam-turbine assembly with M16-M30 metric A286 hex and SHCS. A286 jet engine fasteners.
- Marine diesel / LNG: MAN B&W, Wärtsilä, MTU diesel engines use M10-M24 A286 hex bolts on exhaust valve seats, turbocharger mounting, fuel-injection.
Governing Standards & Material Specifications
Every A286 fastener 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 |
| AMS | 5731 | Bar / forging — solution-treated |
| AMS | 5732 | Bar / forging — solution-treated and aged |
| AMS | 5737 | Bar — solution-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 |
| NACE | MR0175 / ISO 15156-3 | Sour-service hardness limit ≤ HRC 35 |
A286 Metric Bolts vs Alternative Materials
When selecting a fastener material engineers compare A286 against three alternatives: A286 vs Inconel 718 (top-end performance, 3× cost), A286 vs 17-4 PH (cheaper but limited to 315 °C), and A286 vs Waspaloy (sustained service > 700 °C). A286 wins the 540-700 °C cost-per-MPa-of-retained-preload comparison cleanly. See the consolidated A286 equivalent grades reference for full alloy alternatives.
How to Specify A286 Metric Bolts
A complete a286 metric bolts callout should include: material spec, heat-treatment condition, dimensional standard, size, thread tolerance class, surface finish, marking, inspection certificate. Example callout:
Hex bolt, ISO 4014, A286 (UNS S66286), ASTM A453 grade 660 Class A, ST+A, M16 × 2.0 × 80 mm, 6g, pickled-and-passivated, head-marked ‘A286’ + ‘GR 660’ + lot + ‘TB’, EN 10204 3.1.
A286 Metric Bolts — Frequently Asked Questions
What is the difference between A286 metric bolts and A286 inch bolts?
Material is identical (UNS S66286 / ASTM A453 grade 660). Thread system differs: metric uses M-designation (M5-M64) per ISO 1502 with mm pitch; inch uses UNC / UNF / 8-UN per ASME B1.1 with TPI (threads per inch). Wrench sizes also differ — metric AF in mm, inch AF in fractional inches.
What is the standard pitch for an A286 metric bolt?
Coarse pitch is the default per ISO 261 (M6 = 1.0, M8 = 1.25, M10 = 1.5, M12 = 1.75, M16 = 2.0, M20 = 2.5). Fine pitch (M8 × 1.0, M10 × 1.25, M16 × 1.5) used for high-vibration and aerospace applications where thread engagement length is critical.
What thread tolerance applies to A286 metric bolts?
Commercial 6g per ISO 1502 (default). Aerospace 4g6g per MIL-S-8879 equivalent — tighter tolerance for fatigue-critical joints. Specify 6g unless drawing requires aerospace tolerance.
Are A286 metric bolts available in fine thread?
Yes — TorqBolt manufactures metric fine-pitch A286 bolts in M8 × 1.0, M10 × 1.25, M12 × 1.25, M14 × 1.5, M16 × 1.5, M18 × 1.5, M20 × 1.5, M22 × 1.5, M24 × 2.0. Used on aerospace high-vibration joints and instrumentation.
What standard is most common for A286 metric hex bolts?
ISO 4014 (partial thread, equivalent to DIN 931) and ISO 4017 (full thread, equivalent to DIN 933) cover ~70 % of A286 metric bolt orders. Older European drawings cite DIN 931/933; modern drawings cite ISO 4014/4017 — dimensions identical.
Can A286 metric bolts pair with non-A286 metric nuts?
Mechanically yes, but galling above 540 °C is a concern for austenitic-stainless mating (304/316 nuts). Match A286 bolts to A286 hex nuts for matched preload, matched magnetic permeability, and anti-galling protection.
Are metric A286 bolts magnetic?
No — magnetic permeability < 1.005 verified per ASTM A342. Suitable for instrumentation, MRI, magnetometer, and electromagnetic-sensitive aerospace and industrial applications.
What head-marking on a metric A286 hex bolt?
Per ASTM F788: head-stamped 'A286' (or 'GR 660' for ASTM A453 traceability) + lot number + manufacturer ID 'TB'. ISO marking does not specify grade markings; TorqBolt adds them for traceability.
What's the longest metric A286 bolt available?
Standard production: 600 mm in M5-M48. Custom-drawing parts to 1000 mm in M16-M64 — special bar stock + extended thread-rolling required. Beyond 1000 mm, use A286 stud bolts (full-thread bar substrate) instead.
Why TorqBolt for A286 Metric Bolts
Three reasons aerospace and gas-turbine OEMs place a286 metric bolts orders with us:
- Vertically integrated supply — VIM-VAR melt sourcing from approved AMS-conforming mills, in-house cold heading + thread rolling + vacuum heat-treatment.
- Aerospace AQMS — AS9100D-certified factory in Mumbai with published quality manual covering A286 fastener-specific failure-mode analysis.
- Lead time discipline — 4-6 weeks for ASTM A453 grade 660 standard sizes, 8-12 weeks for custom-drawing aerospace parts.
30+ years in fastener manufacture; ISO 9001:2015 + AS9100D + PED 2014/68/EU + NORSOK M-650 QTR all current.
Recent A286 Metric Bolts Order Patterns
Active metric A286 bolt order categories: aerospace engine-pylon hex bolts (M16 ISO 4014), automotive turbocharger waste-gate hex flange bolts (DIN 6921, M8), industrial gas-turbine casing-split bolts (M24 ISO 4014), and accessory-gearbox SHCS (M10 ISO 4762).
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