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 Bolts
A286 Fasteners being an austenitic
age-hardenable iron based super alloy stainless steel that is melted as AOD + ESR, AOD
+ VAR, or VIM + VAR is manufactured at TorqBolt. Cres-A286 fasteners have excellent
strength even at high temperatures up to 1500 Degrees Fahrenheit. Alloy A286 Stainless
Fasteners has excellent creep resistance making it excellent for critical high
temperature applications such as jet engine components. A286
Fastener Strength conforming to the ASTM
A453 Grade 660 Class D specification (with a guaranteed yield strength minimum
of 105,000 PSI), but with stress rupture tests carried out to also conform to ASTM
A453 Grade 660 Class A. These provide a tensile strength of 895 MPa (minimum),
0.2% offset yield strength of 725 MPa (minimum), elongation of 15% and reduction of
area of 18%. Hardness is in the range 29-35 HRC.
In general, we also supply ASTM A453 GR 660 heat-treated and tested to conform to grade
B. This provides a tensile strength of 895 MPa (minimum), a lower 0.2 offset yield
strength of 585 MPa (minimum), elongation of 15% and reduction of area of 18%. Hardness
is in the range 24-37 HRC.
A286 Bolt Variants, Browse by Type
TorqBolt manufactures Alloy A286 bolts in every aerospace, industrial and commercial head pattern. Each variant has its own dedicated reference page covering chemistry, dimensions, manufacturing process, inspection scope, applications and FAQ:
- A286 Hex Bolts, DIN 931 / 933, ISO 4014 / 4017, ASME B18.2.1 in M5-M64 / 1/4"-2-1/2". Standard external-hex bolt for jet-engine, gas-turbine and industrial flange bolting.
- A286 CRES Bolts, Aerospace Corrosion-Resistant Steel bolts per NAS 1351 / NAS 6603, MIL-S-8879, AS9100D AQMS. The dominant US-spec aerospace bolt.
- A286 Socket Head Cap Screws (SHCS), Cylindrical head with internal hex socket per ISO 4762 / DIN 912 / NAS 1351 / NAS 6203. M3-M48 for compact joints.
- A286 Shoulder Bolts, Precision unthreaded shoulder + threaded end per ASME B18.3 / ISO 7379 / NAS 1352. h7 / h8 tolerance for pivot and guide-pin applications.
- A286 Metric Bolts, M5-M64 per DIN 931 / 933 / ISO 4014 / 4017 / ISO 4762. Coarse and fine pitch. Default for European, Asian and Indian aerospace and industrial.
- A286 NAS Bolts, National Aerospace Standard NAS 1351 / 1352 / 6203 / 6603-6620 in #4 to 1-1/2". The dominant precision-hardening fastener on US-built aerospace.
- A286 Stud Bolts, Full-thread or partial-thread stud bolts for ASME B16.5 flange joints, ASTM A453 grade 660 high-temperature bolting. M5-M64 + 1/4"-2-1/2".
All variants are forged from the same A286 bar stock (AMS 5731 / 5732), heat-treated per A286 heat treatment standard cycle, and certified per the same A286 chemical composition and A286 mechanical properties.
About A286 Bolts
TorqBolt manufactures Alloy A286 (UNS S66286 / DIN 1.4980) bolts in metric, UNC, UNF and 8-UN inch series, hex-head, socket-head, hex-flange and shoulder bolts in M5 to M64 / 1/4" to 2-1/2" sizes. Each A286 bolt is solution-treated and aged to ASTM A453 grade 660 Class A, delivering 130 ksi (895 MPa) minimum tensile strength, 95 ksi (655 MPa) yield, and retained preload to 700 °C, the proven choice for jet-engine, gas-turbine, turbocharger and exhaust-system bolting where stainless and carbon-steel alternatives lose strength.
A286 Bolt Head Types & Drive Configurations
TorqBolt produces Alloy A286 (UNS S66286) bolts in every head and drive style needed for aerospace, gas-turbine, exhaust and high-temperature service. Head selection is driven by joint geometry, wrenching access and aesthetic finish; drive selection by torque requirement and assembly tooling. Each A286 bolt head is forged or machined from solution-treated bar (AMS 5731) and aged after thread-rolling to develop full 130 ksi tensile strength.
- Hex head, ASME B18.2.1 / DIN 933 / ISO 4017 (full thread) and DIN 931 / ISO 4014 (partial thread). The standard high-strength wrenching geometry; 30-degree internal chamfer per ISO 4014 reduces stress concentration.
- Heavy hex, ASME B18.2.1 thicker head, used on flange bolting per ASME PCC-1 to allow higher preload without head shear.
- Socket head cap (SHCS), ASME B18.3 / ISO 4762 / DIN 912. Hex internal drive (Allen) for compact joints with limited wrench clearance.
- Button head socket cap, ISO 7380 / DIN 7380, low-profile dome, decorative or low-clearance.
- Flat (countersunk) head socket cap, ISO 10642 / DIN 7991, 90-degree countersink for flush mounting.
- Shoulder bolt, ASME B18.3 unthreaded shoulder + threaded end; used as a precision pivot or guide pin.
- 12-point flanged, ASME B18.2.5 / IFI-115, double-hex drive for high-torque jet-engine applications (aerospace specs IFI-115, AS3239).
A286 Bolt Tightening & Torque Practice
A286 bolts are typically pre-stressed to 75 % of room-temperature yield (~71 ksi residual stress) so the joint retains positive clamp at 700 °C operating temperature where the alloy yield drops to ~75 ksi. ASME PCC-1 covers torque vs. tension methods, including elongation measurement, hydraulic tensioning and ultrasonic length-change verification. Anti-galling lubricant (nickel or copper anti-seize) is mandatory above 540 °C; A286 thread surfaces are otherwise prone to galling against austenitic-stainless nuts during tightening. For matched-alloy assembly, A286 bolts pair with A286 hex nuts, or self-locking nuts and lock nuts where vibration retention is required, plus A286 flat washers and lock washers from the same heat lot.
A286 Bolt Applications by Industry
- Aerospace propulsion: jet-engine compressor and turbine bolting, augmentor cases, fuel-system mounting.
- Industrial gas turbines: casing-split bolting, combustor liner attachment, transition-piece fasteners.
- Turbocharger: waste-gate bolts, exhaust manifold flange bolting, V-band clamp studs.
- Oil & gas: downhole tool bolting, NACE MR0175 / ISO 15156 sour-service compliant when hardness ≤ HRC 35 is verified.
- Cryogenic LNG: A286 retains 85 % of room-temperature toughness at -196 °C; used for valve-bonnet and pump-flange bolting on LNG service.
- Nuclear: ASME III subsection NB / NF-permitted material per A453 grade 660 Class A.
Alloy A286 Bolts , Specification Overview
Alloy A286 bolts are the dominant high-temperature fastener choice for the 540-700 °C service envelope. They retain 95 % of room-temperature yield at 540 °C and 70 % at 700 °C, while staying non-magnetic and corrosion-resistant. That combination is why A286 dominates jet-engine compressor and turbine bolting, industrial gas-turbine casings, automotive turbocharger waste-gates and offshore subsea equipment.
The alloy is a precipitation-hardening iron-nickel-chromium superalloy, nominal composition 53Fe-25Ni-15Cr-2Ti-1.3Mo with a small boron addition that dramatically improves stress-rupture life at temperature. Strengthening comes from gamma-prime Ni₃(Ti,Al) precipitates developed during the standard 980 °C solution-treatment + 720 °C / 16-hour aging cycle defined by ASTM A453 grade 660 Class A.
A286 Bolts Governing Standards & Specifications
TorqBolt manufactures every a286 bolts to the applicable industry standard. The matrix below lists the principal specifications , material, dimensional, inspection, that a286 bolts are released against. EN 10204 type 3.1 mill certificates ship with every order; type 3.2 third-party-witnessed inspection is available for nuclear, offshore and customer-mandated source-surveillance contracts.
| Authority | Specification | Coverage |
|---|---|---|
| ASTM | A453 grade 660 Class 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) |
| ASME | B18.2.1 / B18.3 | Hex bolt / socket head cap screw dimensions |
| DIN | 931 / 933 / 912 / 7991 / 6921 | Metric hex / socket / countersunk / flange head |
| ISO | 4014 / 4017 / 4762 / 7380 / 10642 | Metric hex / socket / button / countersunk |
| NAS | 1351 / 1352 / 6203 | Aerospace socket-head cap screws (12-point, hex) |
| MIL-DTL | 23054 / MS90725 / MS90726 | Aerospace machine bolts and 12-point bolts |
| EN | 10204 3.1 / 3.2 | Mill / third-party-witness certification |
| NACE | MR0175 / ISO 15156-3 | Sour-service hardness limit ≤ HRC 35 |
| NORSOK | M-650 | Offshore prequalification QTR |
A286 Bolts Sizes & Available Patterns
TorqBolt manufactures A286 bolts in the full metric (M5 to M64), UNC, UNF and 8-UN inch (1/4" to 2-1/2") ranges. Standard head and drive options are listed below; custom-drawing parts are quoted to size.
| Head Pattern | Standard | Metric range | Inch range | Drive |
|---|---|---|---|---|
| Hex head | DIN 931 / 933 / ISO 4014 / 4017 | M5, M64 | 1/4" , 2-1/2" | External hex |
| Heavy hex | ASME B18.2.1 | M12, M64 | 1/2" , 2-1/2" | External hex |
| Socket head cap (SHCS) | ISO 4762 / DIN 912 / ASME B18.3 | M3, M48 | #4 , 1-1/2" | Hex socket |
| Button head | ISO 7380 / DIN 7380 | M3, M16 | #4 , 5/8" | Hex socket / Torx |
| Flat (countersunk) | ISO 10642 / DIN 7991 | M3, M30 | #4 , 1-1/4" | Hex socket / Torx |
| Shoulder bolt | ASME B18.3 | M5, M30 | 1/4" , 1" | Hex socket |
| 12-point (Spline) | AS3239 / IFI-115 | M5, M24 | 1/4" , 1" | 12-point external |
A286 Bolts Manufacturing Process
Every a286 bolts TorqBolt ships traces back to a vacuum-induction-melted plus vacuum-arc-remelted (VIM-VAR) ingot meeting AMS 5731 / 5732 chemistry. The complete manufacturing route is:
- Melt: VIM-VAR or VIM-ESR ingot to AMS 5731 / 5732 chemistry; element ranges per ASTM A453 grade 660.
- Cogging & bar production: ingot broken down at 1095 °C, finished hot- or cold-drawn to bar with controlled grain size.
- Cold or hot heading: head pattern formed by upsetting in a multi-station header. Cold heading for sizes ≤ M16; hot heading for larger sizes and 12-point geometry.
- Thread rolling: threads rolled (not cut) to maximise surface fatigue strength and grain flow continuity. Class 6g/2A standard.
- Solution treatment: 980 °C / 1800 °F for one hour per inch, oil-quench. Vacuum or controlled-atmosphere furnace for aerospace lots.
- Precipitation aging: 720 °C / 1325 °F for 16 hours, air-cool. Develops gamma-prime Ni₃(Ti,Al) precipitates; hardness 277-302 HBW (30-32 HRC).
- Surface finish: pickle (HNO₃ / HF) or grit-blast to remove oxide; passivation per ASTM A967 if specified.
- Inspection: dimensional CMM check, hardness traverse, tensile coupon, hardness verification per NACE MR0175 if invoked, NDT (LPI / UT) per drawing.
- Marking & packing: head-marked with grade and lot per drawing; barcoded with heat traceability label; corrosion-protective packaging.
Lot traceability is maintained from VIM-VAR heat number through finished-part inspection. Customer-witness sampling, NDT (LPI / UT / RT), and radiographic certification are available on contracts that invoke AS9100D, NORSOK M-650 QTR or nuclear ASME III subsection NB.
Inspection & Certification on A286 Bolt Lots
Each bolt lot ships with a signed inspection certificate. Aerospace orders default to AS9100D first-article reporting per AS9102 on the first part of any new drawing or revision. Industrial flange-bolting orders default to EN 10204 type 3.1; sour-service and offshore orders step up to type 3.2 with third-party witness present at heat-treat release and tensile testing.
- NACE MR0175 hardness verification on every heat, Vickers traverse confirmed below HV 327 (HRC 35).
- Magnetic permeability check on every coil; A286 is austenitic and must read < 1.005 µᵣ.
- Thread-gauging on a 100 % basis using calibrated GO / NO-GO gauges.
- Penetrant inspection (LPI per ASTM E1417) on aerospace lots.
- Heat-treat traverse: hardness sampling at four positions on every heat-treatment batch.
- Salt-spray testing per ASTM B117 when a passivation or plating spec is invoked.
Our quality file maintains the audited NORSOK M-650 QTR for A286 fastener manufacture, renewed every 5 years. Customer-witnessed source surveillance is welcomed; recent witnesses include Kuwait Oil Company, Adnoc Sour Gas, and a Tier 1 jet-engine OEM.
A286 Bolt Applications by Industry
Aerospace propulsion
A286 bolts hold together every modern jet engine. Compressor disc-to-disc bolting, turbine wheel attachment, augmentor case bolting, fuel-system mounting, exhaust-cone fasteners. The non-magnetic property protects flight instrumentation; the 700 °C ceiling matches the working temperature of the high-pressure compressor; the AMS 5732 spec is invoked on virtually every commercial and military engine drawing.
Industrial gas turbines
Land-based gas turbines (GE 9F-class, Siemens SGT-800, Mitsubishi M501) use A286 bolts on casing-split flanges, combustor liner attachment, transition-piece retention and inlet-guide-vane actuator pivots. Service intervals run 24,000-32,000 hours between hot-gas-path inspections; A286 fasteners survive 5+ inspection cycles without re-tensioning.
Turbocharger and exhaust systems
Diesel and gasoline turbocharger waste-gate bolts, exhaust manifold flange bolting, V-band clamp studs. Operating temperatures peak above 850 °C in the turbine housing, dropping to 600-700 °C at the bolt location , the upper edge of A286’s envelope.
Oil & gas downhole
Sour-service downhole tool bolting, packer-element retention, perforating-gun assembly. NACE MR0175 hardness limit ≤ HRC 35 is met by aging at the high end of the A286 spec window. Sub-zero pressure-housing bolting on cryogenic LNG service down to −196 °C.
Nuclear pressure-vessel bolting
ASME III subsection NB-2000 lists A453 grade 660 as a permitted bolting material for pressure-retaining components. Used on PWR pressuriser flange bolting, steam-generator hand-hole studs and primary-coolant-pump casings.
A286 Bolts vs Alternative Materials
Bolt-material decisions usually weigh A286 against 17-7 PH (cheaper but limited to 315 °C), Inconel 718 (top-end performance, 3× cost), and A4-80 stainless (a B7 substitute for moderate-temperature corrosion service). A286 wins the 540-700 °C cost-per-MPa-of-retained-preload comparison cleanly.
| Property | A286 (UNS S66286) | 17-7 PH | Inconel 718 | A4-80 (316) |
|---|---|---|---|---|
| Service ceiling | 700 °C | 315 °C | 700 °C | 425 °C |
| RT yield | 655 MPa | 1100 MPa | 1035 MPa | 600 MPa |
| Magnetic | No | Yes | No | No |
| Sour service ≤ HRC 35 | Yes | No | Yes (≤40) | Yes |
| Cost index | 1.0× | 0.4× | 3.0× | 0.5× |
A286 is the sweet-spot fastener material when service temperature exceeds 315 °C (the 17-7 PH ceiling) but the application can’t justify a 3× cost jump to Inconel 718. Roughly 70 % of all jet-engine and industrial-gas-turbine bolting falls in this 540-700 °C envelope, which is why A286 is the highest-volume aerospace superalloy fastener material in the world.
How to Specify an A286 Bolt
A complete A286 bolt callout on a drawing or purchase order should include all eight elements:
- Material spec: “ASTM A453 grade 660 Class A” (or AMS 5732 / 5737 for aerospace).
- Heat-treatment condition: solution-treated and aged (ST+A); aging cycle if non-standard.
- Head and dimensional standard: e.g. “DIN 931” (hex), “ISO 4762” (socket head), “NAS 6203” (aerospace SHCS).
- Size: nominal diameter × pitch × length, e.g. “M16 × 2.0 × 80 mm”.
- Thread tolerance class: 6g (metric) or 2A / 3A (inch); 3A for aerospace precision.
- Surface finish: pickled (No.1), passivated per ASTM A967, or anti-galling-coated (silver / nickel anti-seize).
- Marking: head-stamp grade + lot + manufacturer ID per drawing or governing standard.
- Inspection certificate: EN 10204 3.1 (default) or 3.2 (third-party-witness), specify on PO.
Example complete callout: “Hex bolt, ASTM A453 grade 660 Class A, ST+A, DIN 931, M16 × 2.0 × 80 mm, 6g, pickled-and-passivated, head-marked ‘A286’ + lot, EN 10204 3.1, NACE MR0175 hardness verified.”
Why TorqBolt for A286 Bolts
Three reasons jet-engine OEMs and gas-turbine specialists place A286 bolt orders with us:
- Vertically integrated supply: VIM-VAR melt sourcing from approved AMS-conforming mills, in-house cold heading + thread rolling + vacuum heat-treatment. No outsourced critical step.
- Aerospace AQMS: AS9100D-certified factory in Mumbai with a published quality manual covering bolt-specific failure-mode analysis (preload retention, hydrogen embrittlement, thread fatigue).
- Lead time discipline: 4-6 weeks for ASTM A453 grade 660 Class A standard sizes, 8-12 weeks for custom-drawing aerospace parts. No surprises.
30-plus years in fastener manufacture; no MOQ on stocked DIN / ISO patterns; ISO 9001:2015 + AS9100D + PED 2014/68/EU + NORSOK M-650 QTR all current. Lot traceability runs from VIM-VAR melt heat number through finished-part packaging.
Recent A286 Bolt Order Patterns
Orders we've fulfilled in the last two quarters give a sense of where A286 bolts are most in demand: jet-engine compressor-disc retention M16-M24 (supplied to two Tier 1 OEMs in matched-pair lots), waste-gate housing bolting M8-M12 for a turbocharger manufacturer in Pune, exhaust manifold flange bolting M10-M14 for a marine diesel rebuilder in Singapore, and downhole-tool body retention 1" UNF for an oilfield-services contractor in Abu Dhabi. The recurring theme: 540-700 °C cyclic service with a non-magnetic requirement.
A note from QA: every A286 bolt batch we ship has been hardness-traversed at four cross-section positions per heat. This catches the rare under-aged bolt that escapes the time-temperature controller, a 2018 audit on one of our oldest furnaces found a 4 % dropout rate before we tightened the trace; it has been zero since the four-point sampling was made standard.
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