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 CRES Screws
A286 CRES screws, where CRES = Corrosion-Resistant Steel, the US aerospace shorthand for stainless and precipitation-hardening-stainless fasteners, are the dominant non-magnetic precipitation-hardening screws on US aerospace assemblies. TorqBolt manufactures CRES A286 screws to NAS 1351 / NAS 1352 / NAS 6203 (socket head cap), NAS 514 (flat head countersunk), MS 35206 / MS 51957 (machine screws), and BACS (Boeing) standards. Material is solution-treated and aged to ASTM A453 grade 660 Class A from AMS 5732 bar. CRES classification confirms corrosion resistance against jet-engine combustion gas, salt-fog, and marine atmospheres at temperatures from cryogenic to 700 °C. See parent A286 screws, sister variants socket head cap screws, flat head screws, metric screws, parent CRES bolts and the canonical chemical composition + heat treatment.
About A286 CRES Screws
CRES A286 screws serve the same aerospace role as CRES A286 bolts but on lighter-load joints, accessory mounting, panel attach, instrument bolting, ventilation duct hardware. Material is identical (UNS S66286 / ASTM A453 grade 660 / AMS 5732) but production is optimized for screw size ranges (#4 to 1/2 inch) where cold-heading throughput dominates over forging. Each CRES A286 screw is cold-headed from AMS 5731 bar, thread-rolled to MIL-S-8879 Class 3 tolerance, solution-treated 1650 °F + aged 1325 °F × 16 h, passivated per ASTM A967, and head-stamped per applicable NAS / MS marking standard. Magnetic permeability < 1.005 verified per ASTM A342 on every coil.
A286 CRES Screw Head Patterns & Aerospace Standards
TorqBolt produces CRES A286 screws in five primary head/drive configurations:
- NAS 1351 / 1352 (socket head cap), Aerospace SHCS, internal hex drive, cylindrical head, MIL-S-8879 thread. The most common CRES A286 screw.
- NAS 6203 (reduced-shank SHCS), Reduced-diameter shank for fatigue performance. Specified on aerospace accessory mounting and high-cycle structure attach.
- NAS 514 (100° flat head countersunk), Aerospace flat head screw with 100° countersink, used on aircraft skin attach, panel mounting, fuselage internal hardware.
- MS 35206 / MS 51957 (machine screws), MIL-spec machine screws, slotted, Phillips, or hex socket drive. Used on US military airframe and engine assemblies.
- BACS (Boeing internal-spec), Boeing CRES screw patterns, manufactured to MIL-S-8879 with traceability per BAC 5004. Used on Boeing 737-787 maintenance and overhaul.
A286 CRES Screw Sizes & NAS Reference
| NAS part number | Size | Thread | Head ⌀ | Drive | Min. tensile (lbf) |
|---|---|---|---|---|---|
| NAS 1351-N0 | #4 (3 mm) | 40 UNC | 0.183 inch | Hex socket 3/32 | 950 |
| NAS 1351-N1 | #6 (3.5 mm) | 32 UNC | 0.226 inch | Hex socket 7/64 | 1,400 |
| NAS 1351-N2 | #8 (4 mm) | 32 UNC | 0.270 inch | Hex socket 9/64 | 1,900 |
| NAS 1351-N3 | #10 (5 mm) | 32 UNF | 0.312 inch | Hex socket 5/32 | 2,800 |
| NAS 1351-N4 | 1/4 (6 mm) | 28 UNF | 0.375 inch | Hex socket 3/16 | 4,800 |
| NAS 514P-08-08 | 8-32 (4 mm) | 32 UNC | Flat 100° CSK | Phillips #2 | 1,600 |
| NAS 514P-10-10 | 10-32 (5 mm) | 32 UNF | Flat 100° CSK | Phillips #2 | 2,400 |
| MS 51957-30 | #10 (5 mm) | 32 UNF | 0.312 inch | Phillips #2 | 2,300 |
A286 CRES Screws Manufacturing Process
Every a286 cres screws 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 sourcing: AMS 5731 / 5732 chemistry from approved aerospace mills. AS9100D AQMS lot traceability.
- Vacuum-degassed bar input: Bar drawn to NAS 1351 / 514 starting blank ⌀. Aerospace cold-heading uses vacuum-degassed bar to minimize void formation.
- Cold heading (single-station for #4-#10): Single-station header forms head + cone in one stroke for sizes #4 through #10. Aerospace cold-heading machines run with closed-loop force monitoring.
- Cold heading (multi-station for 1/4-1/2 inch): Multi-station header for 1/4-1/2 inch sizes, extrusion, cone, head trim, hex socket forming or 100° countersink in sequence.
- Thread rolling MIL-S-8879 Class 3: Roll-formed threads to MIL-S-8879 Class 3A tolerance. Aerospace fatigue performance requires rolled threads, not cut.
- Vacuum solution treatment: 1650 °F (899 °C) per AMS 5737 / ASTM A453 Class A. Vacuum environment prevents IGA / oxide contamination.
- Precipitation aging: 1325 °F (718 °C) for 16 hours, air-cool. Aerospace temperature control ±5 °C for hardness consistency.
- Passivation + permeability check: Passivate per ASTM A967 Type II; verify magnetic permeability < 1.005 per ASTM A342 on every coil.
- AS9102 first-article + lot serialization: First-article on every new drawing/revision; lot serialization 1-N per BAC 5004 / NAS 100.
A286 CRES Screws Inspection & Certification
Each lot ships with a signed inspection certificate. Aerospace lots default to AS9102 FAI reporting under our AS9100D AQMS coverage. 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 MIL-S-8879 Class 3.
- 100 % hex socket dimension check (NAS 1351) or Phillips drive check (NAS 514).
- 100 % countersink angle 100° verification on NAS 514 flat-head screws.
- Hardness traverse 4-point Vickers per heat-treat batch.
- Magnetic permeability < 1.005 per ASTM A342, every aerospace coil.
- LPI per ASTM E1417 Class 1 on every aerospace lot.
- Tensile coupon from each heat per ASTM E8 + elevated-temperature per E21.
- AS9102 first-article on every new drawing/revision; lot 1-N serialization per BAC 5004.
A286 CRES Screws Torque & Assembly Practice
CRES A286 screws torque per the airframe or engine assembly manual (Boeing 737 SOPM, F-16 -10 manual, etc.). Aerospace torque tables typically pre-stress to 60-65 % of yield for cycling joints, 70-75 % for static. NAS 514 100° countersunk screws: tighten to seat without crushing the conical head bearing area, over-torque deforms the countersink and loses preload. NAS 1351 SHCS: torque to MIL-HDBK-60 default values when assembly manual silent. Above 540 °C apply nickel anti-seize to threads.
A286 CRES Screw Applications by Industry
CRES A286 screws appear on every modern US-spec aerospace and defence assembly:
- Aircraft skin & panel attach: NAS 514 100° flat-head countersunk screws on aircraft skin panels, flush-mount aerodynamic profile, AMS 5732 material, magnetic permeability isolation.
- Engine accessory mounting: NAS 1351 SHCS on accessory gearbox attach, fuel-pump mounting, sensor brackets. A286 jet engine fasteners.
- Avionics & instrumentation: CRES A286 machine screws on radio rack, autopilot, flight management system mounting, non-magnetic isolation from compass and nav-sensor.
- Cabin / interior structure: BACS CRES screws on cabin sidewall, overhead bin attach, lavatory bulkhead, cabin maintenance access fasteners.
- Defence airframe: MS 35206 / MS 51957 CRES A286 machine screws on F-15, F-16, F-22, F-35 internal hardware.
- Space launch: CRES A286 screws on SpaceX Crew Dragon, Boeing CST-100, ULA upper-stage avionics and instrumentation rack mounting.
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 CRES Screws 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). Within the 540-700 °C service envelope A286 is the dominant cost-performance choice for non-magnetic, oxidation-resistant bolting. See the consolidated A286 equivalent grades reference for full alloy alternatives.
How to Specify A286 CRES Screws
A complete a286 cres screws callout should include: material spec, heat-treatment condition, dimensional standard, size, thread tolerance class, surface finish, marking, inspection certificate. Example callout:
NAS 1351-N3, A286 / UNS S66286, ASTM A453 grade 660 Class A, ST+A, 10-32 UNF × 0.75 inch, MIL-S-8879 Class 3 thread, magnetic permeability < 1.005, passivated per A967, head-stamped ‘NAS 1351-N3’ + lot + ‘TB’, AS9102 first-article on lot.
A286 CRES Screws, Frequently Asked Questions
What does CRES mean on an A286 screw?
CRES = Corrosion-Resistant Steel, the US aerospace term for stainless and precipitation-hardening-stainless fasteners including A286, 17-4 PH, 17-7 PH, AM-355. CRES designation appears on US-spec aerospace drawings (NAS, MS, MIL, BACS) to distinguish from carbon-steel PHCS or LAS screws.
Are CRES A286 screws the same as commercial A286 screws?
Material is identical (UNS S66286 / ASTM A453 grade 660 / AMS 5732). Manufacturing differs: CRES screws produced under AS9100D AQMS with MIL-S-8879 Class 3 thread, AS9102 first-article inspection, and lot serialization 1-N. Commercial A286 screws use ISO 4762 / DIN 912 commercial thread Class 6g and EN 10204 3.1 mill cert only.
What head marking on a CRES A286 NAS screw?
Per NAS marking convention: head-stamped NAS part number (e.g. 'NAS 1351-N3') + 'A286' material + lot number + manufacturer 'TB'. Stamp depth 0.05-0.10 mm per drawing.
What's the difference between NAS 1351 and NAS 514 A286 screws?
NAS 1351 = socket head cap screw (SHCS), cylindrical head, internal hex drive. NAS 514 = 100° flat head countersunk screw, flush-mount, Phillips or slotted drive. NAS 1351 for general aerospace bolting; NAS 514 for aircraft skin and panel attach.
Are CRES A286 screws magnetic?
No. Magnetic permeability < 1.005 verified per ASTM A342 on every aerospace coil. Critical for avionics, MRI, magnetometer, and electromagnetic-sensitive aerospace assemblies.
Can CRES A286 screws be re-used?
Aerospace primary structure: NO, single-use only per OEM SRM. Aerospace secondary / accessory mounting: yes with thread-distortion and head-stamp inspection. Industrial / commercial: yes, multiple cycles permitted with documented torque.
What thread tolerance for CRES A286 screws?
MIL-S-8879 / ASME B1.13M Class 3A, tighter than commercial 2A. Required for aerospace fatigue per NAS 1351 / 514 acceptance criteria.
What screwdriver bit for a NAS 514 flat head A286 screw?
Phillips #2 for #6 / #8 / #10 sizes; Phillips #3 for 1/4 inch. Some NAS 514 variants specify slotted drive or Torx, check the specific dash-number suffix on the drawing.
What's the longest CRES A286 NAS screw available?
Standard production: NAS 1351 to 3.0 inch length, NAS 6203 to 2.5 inch, NAS 514 to 2.0 inch. Beyond standard length use NAS 6603 12-point bolt or custom-drawing part.
Why TorqBolt for A286 CRES Screws
Three reasons aerospace and gas-turbine OEMs place a286 cres screws 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 of fastener-manufacturing track record. Active certifications cover ISO 9001:2015, AS9100D AQMS, PED 2014/68/EU and NORSOK M-650 QTR.
Recent A286 CRES Screws Order Patterns
Active CRES A286 screw applications: NAS 1351 SHCS on aerospace avionics rack mounting, NAS 514 100° flat head on aircraft skin attach, MS 51957 Phillips machine screws on fighter-jet instrumentation, and BACS CRES screws on Boeing 737 cabin maintenance hardware.
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