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 Screws
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 Screw Variants, Browse by Type
TorqBolt manufactures Alloy A286 screws across every head and drive style. Each variant has its own dedicated reference page:
- A286 Socket Head Cap Screws (SHCS), Cylindrical head, internal hex drive per ISO 4762 / DIN 912 / NAS 1351 / NAS 6203 in M3-M48 / #4-1-1/2".
- A286 CRES Screws, Aerospace Corrosion-Resistant Steel screws per NAS 1351 / 514 / MS 51957 / BACS, MIL-S-8879 thread tolerance.
- A286 Flat Head Countersunk Screws, 100° (NAS 514 / MS 24693) and 90° (DIN 7991 / ISO 10642) countersunk in M3-M30 / #4-1/2".
- A286 Metric Screws, ISO 4762 SHCS, ISO 7380 button head, ISO 10642 flat head, DIN 933 hex, DIN 7984 low-head in M3-M48.
- A286 Button Head Screws, Low-profile dome head with hex socket per ISO 7380 / DIN 7380 / DIN 6912 in M3-M16.
- A286 Cap Screws, Hex cap (ASME B18.2.1), socket head cap (ISO 4762), 12-point cap (NAS 6603), general-purpose threaded-hole cap screws in M3-M48.
- A286 Set Screws, Headless socket set screws, flat / cone / cup / dog point per ISO 4026-4029 / DIN 913-916 in M3-M20.
All A286 screws are cold-headed from A286 bar stock, thread-rolled, then solution-treated and aged per A286 heat treatment. Magnetic permeability < 1.005 verified per ASTM A342 on every aerospace lot.
About A286 Screws
TorqBolt manufactures Alloy A286 (UNS S66286) screws, hex-head cap screws, socket-head cap screws, button-head, flat-head, shoulder, set, and self-drilling/self-tapping screws, in metric, UNC, UNF, and aerospace NAS / MIL-SPEC formats. Each A286 screw is heat-treated to ASTM A453 grade 660 Class A and supplied with EN 10204 3.1 or 3.2 certification, delivering the non-magnetic, oxidation-resistant, creep-stable performance demanded by jet engines, instrumentation and high-temperature process equipment.
A286 Screw Drive Types & Recess Geometries
Alloy A286 screws are differentiated from bolts by full-length threading, smaller head proportion and direct torquing of the head into the mating tap. TorqBolt machines or cold-heads A286 screws from AMS 5731 / 5732 / 5737 stock and ages every part to 130 ksi tensile minimum.
- Hex socket (Allen), ANSI B18.3 / ISO 4762 / DIN 912. Highest torque transfer for compact heads.
- Hex external, standard hex head, wrenched externally per DIN 933.
- Cross-recess Phillips type II, ANSI B18.6.3 / ISO 8764, designed to cam-out at maximum torque.
- Pozidriv, deeper engagement than Phillips, no cam-out.
- Torx (six-lobe internal), ASME B18.6.1 / ISO 10664, transmits 33 % more torque than Phillips at equivalent recess depth.
- Torx Plus, six-rib drive, eliminates ramp angle; 30 % more bit life than standard Torx.
- Square (Robertson), self-centering, allows one-handed driving.
- Tamper-resistant, pin-Torx, snake-eye, three-wing, for security applications.
A286 Screw Specialty Heads & Aerospace Standards
- Cap screw (hex socket), ASME B18.3 high-strength.
- Button head socket cap, ISO 7380, low-profile dome.
- Flat (countersunk) socket cap, ISO 10642 (90°), aerospace 100° per NAS6203.
- Shoulder screw, ASME B18.3 with unthreaded ground shoulder.
- Set screw, ASME B18.3.1M, full-thread; cup, cone, oval, flat, dog points.
- Self-drilling / self-tapping, A286 hardened by aging cuts mating thread without pre-drilling.
Aerospace standards covered: NAS6203 / NAS1351 / NAS1352, NAS1080 / NAS1081, MS90725 / MS90726 / MS9556, MIL-DTL-23054, AN3 / AN4, AS3239.
A286 Screw Service Conditions
A286 screws are specified where 17-7 PH hits its 315 °C limit but the application can’t justify Inconel 718 (~750 °C limit, 3 × cost). Typical envelope: 540-700 °C continuous service, cyclic loading, fatigue, corrosive environment, non-magnetic requirement.
Alloy A286 Screws , Specification Overview
A286 screws hold together the most demanding precision assemblies on Earth: jet-engine accessory drives, exhaust nozzle skin, gas-turbine fuel-system manifolds, rocket-motor structural fittings, vacuum-chamber feedthroughs and high-temperature instrumentation. They are specified instead of 17-7 PH (315 °C limit), instead of 18-8 stainless (creeps and loses preload above 480 °C), and instead of Inconel 718 (3 × the cost) wherever the service envelope sits between 540 °C and 700 °C.
The defining property is preload retention through thermal cycles. An A286 screw torqued to 75 % of room-temperature yield retains 75 % of that initial clamp force after 1000 hours at 700 °C, a relaxation rate roughly 4 × better than 17-4 PH and 10 × better than carbon steel.
A286 Screws Governing Standards & Specifications
TorqBolt manufactures every a286 screws to the applicable industry standard. The matrix below lists the principal specifications , material, dimensional, inspection, that a286 screws 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 | Screw material spec |
| AMS | 5731 / 5732 / 5737 | Bar / forging stock |
| ASME | B18.3 / B18.6.3 / B18.6.1 / B18.3.1M | Socket / machine / set screw dimensions |
| ISO | 4762 / 7380 / 10642 / 14580 / 14583 | Metric socket / button / countersunk / Torx |
| DIN | 912 / 7380 / 7991 / 6912 / 7984 | Metric socket / button / countersunk / low-head |
| NAS | 1351 / 1352 / 1080 / 1081 / 6203 | Aerospace socket / button / 12-point |
| MIL-DTL | 23054 / MS9556 / MS27039 | Aerospace machine and structural screws |
| AS | 3239 / 9100D | 12-point bolt; aerospace AQMS |
| EN | 10204 3.1 / 3.2 | Mill / third-party cert |
| NACE | MR0175 / ISO 15156-3 | Sour service ≤ HRC 35 |
A286 Screws Sizes & Available Patterns
A286 screws are differentiated from bolts by full-length threading, smaller head proportion and direct head-torquing into a tapped hole. TorqBolt produces every drive geometry , hex socket, Torx, Phillips, square, Torx Plus, in metric and inch series.
| Head & Drive | Standard | Metric range | Inch range | Tip |
|---|---|---|---|---|
| Socket head cap (SHCS) | ISO 4762 / DIN 912 / ASME B18.3 | M2 , M48 | #0, 1-1/2" | Plain |
| Button head SHCS | ISO 7380 / DIN 7380 | M2 , M16 | #0, 5/8" | Plain |
| Flat head (countersunk) | ISO 10642 / DIN 7991 / NAS 1351 (100°) | M2 , M30 | #0, 1-1/4" | Plain |
| Low head SHCS | DIN 7984 | M3 , M24 | #4, 1" | Plain |
| Cheese head | DIN 84 / ISO 1207 | M2 , M10 | #0, 3/8" | Plain |
| Set screw (cup pt.) | ISO 4029 / DIN 916 | M2 , M24 | #0, 1" | Cup / cone / dog / oval / flat |
| Shoulder screw | ASME B18.3 | M5 , M30 | 1/4", 1" | Ground shoulder |
A286 Screws Manufacturing Process
Every a286 screws 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 ingot to AMS 5731 / 5737 chemistry.
- Bar & wire: hot-rolled and cold-drawn to wire feedstock for cold-heading.
- Cold heading (small sizes): head form upset at room temperature on a 4-die / 5-blow header.
- Hot heading (larger sizes / 12-point): head form upset at 980 °C in a heated die.
- Recess forming: Hex socket pressed simultaneously with head; Torx or Phillips formed in a separate punch operation.
- Thread rolling: threads rolled (not cut) on a flat-die or planetary-die roller. 6g / 2A standard.
- Solution treatment: 980 °C / 1800 °F, oil-quench, vacuum or controlled atmosphere for aerospace.
- Precipitation aging: 720 °C / 1325 °F / 16 h, air-cool.
- Surface finish: passivation per ASTM A967, or silver-plate per AMS 2410 for anti-galling, or dry-film lubricant per drawing.
- Inspection: dimensional CMM, hardness, recess engagement-torque check, head-stamp verification, NDT to drawing.
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.
A286 Screw Quality Release
Screws differ from bolts in two inspection priorities: drive-recess engagement (the bit must transmit full torque without cam-out) and head-stamp legibility (aerospace traceability depends on the head mark surviving installation torque). We add the following checks beyond standard fastener inspection:
- Drive-recess depth gauged on every part to NAS / MS recess-engagement minimums.
- Recess torque-test per first-piece , the bit must rotate the screw to nominal torque without slipping.
- Head-stamp depth verified at 50× magnification, too shallow loses traceability, too deep weakens the head section.
- Thread runout to head-bearing-face geometry per AS 8879 or DIN 13 fine-thread spec.
- FAI per AS9102 on every new part number or revision change for aerospace customers.
- Salt-spray after passivation per ASTM A967 or AMS 2410 silver-plate per drawing.
For NAS / MS / MIL-DTL-numbered screws we ship under an AS9100D-aligned quality manual. Each shipment carries a Statement of Conformance plus the EN 10204 mill cert.
A286 Screw Applications by Industry
Aerospace propulsion and structures
NAS / MS / MIL-DTL aerospace screws , hex socket cap, button head, 100-degree countersunk, 12-point spline. Engine accessory mounting, fuel-control unit attachment, generator drive bracket, exhaust-nozzle inner skin to outer cone fastening.
Industrial gas turbines and turbomachinery
Combustor casing through-bolting, transition-piece floating-pin retention, secondary-air seal-strip attachment. Service intervals 24,000-32,000 hours between hot-section inspections.
High-temperature instrumentation and electronics
Thermocouple-feedthrough screws, heat-treat-furnace door retainers, vacuum-flange ConFlat-style sealing screws on UHV chambers above 250 °C.
Cryogenic LNG and rocket propellant systems
Liquid-oxygen and liquid-hydrogen valve-bonnet screws, manifold attachment, sensor-port retention. A286 stays ductile to −253 °C (LH₂) while austenitic stainless suffers carbide-precipitation embrittlement.
Specialty laboratory and medical
MRI-compatible non-magnetic screws, mass-spectrometer housings, electron-microscope vacuum chamber lids, all benefit from A286’s non-magnetic / corrosion-resistant / clean-machinable profile.
A286 Screws vs Alternative Materials
For aerospace and instrumentation screws the alternatives are usually 17-7 PH (where temperature stays under 315 °C and the cheaper alloy is acceptable) and Inconel 718 (where cost permits). A2-70 plain stainless is the commodity baseline for non-thermal service. A286 owns the middle ground.
| Property | A286 screw | 17-7 PH | Inconel 718 | A2-70 (304) |
|---|---|---|---|---|
| Service ceiling | 700 °C | 315 °C | 700 °C | 425 °C |
| RT tensile | 895 MPa | 1240 MPa | 1240 MPa | 700 MPa |
| Magnetic | No | Yes | No | No |
| Aerospace spec | NAS 1351 / MIL-DTL-23054 | AMS 5528 | AMS 5662 | N/A |
| Cost index | 1.0× | 0.4× | 3.0× | 0.3× |
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 Screw
- Material spec: ASTM A453 grade 660 Class A or AMS 5731 / 5737.
- Head & drive: e.g. socket head cap, hex socket drive (ISO 4762).
- Size: nominal × pitch × length, e.g. M8 × 1.25 × 25 mm.
- Thread tolerance: 6g (metric) / 2A or 3A (inch); 3A for aerospace.
- Surface finish: passivated, silver-plated, or dry-film lubricated per drawing.
- Marking: head stamp grade and lot per drawing.
- Inspection: EN 10204 3.1 (default), 3.2 if invoked.
Example: “Socket head cap screw, ASTM A453 grade 660 Class A, ST+A, ISO 4762, M8 × 1.25 × 25, 6g, silver-plate per AMS 2410, head-marked ‘A286’ + lot, EN 10204 3.1.”
Why TorqBolt for A286 Screws
A286 screws are a high-mix, low-volume product. We hold inventory on the most-asked DIN / ISO patterns; everything else is single-piece machinable:
- Stocked DIN / ISO patterns: socket head cap (DIN 912), button head (DIN 7380), countersunk (DIN 7991), low head (DIN 7984) in M3 to M24 across our standard length range.
- Single-piece NAS / MS: no batch minimum on aerospace drawings. We'll machine one specimen for first-article testing on a customer drawing then quote production after AS9102 release.
- Drive geometry expertise: hex socket, Torx, Torx Plus, Pozidriv, square , full equipment library plus custom recess geometry to drawing.
30-plus years of fastener manufacture; AS9100D + ISO 9001:2015 + PED + NORSOK certifications; full lot traceability; stamped head-mark on every part.
A286 Screw Order Mix
About 60 % of our screw orders are stocked DIN / ISO socket-head and button-head patterns shipping in 24-72 hours. Aerospace single-piece NAS / MS orders make up about 25 % and run on a 6-8 week build cycle. The remaining 15 % are custom-drawing parts (proprietary head shapes, special drive recesses, captive-washer assemblies) that quote on a 10-12 week lead time.
Personal note on screws: the most common drawing-error we catch in customer prints is the recess-engagement spec. NAS 1351 calls for full-depth engagement to within 0.005" of the design. Half the prints we receive understate this. We ship a free recess-depth gauge with every NAS 1351 first-article so the customer can verify on their own bench.
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