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 Washers
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 Washer Variants, Browse by Type
TorqBolt manufactures Alloy A286 washers in flat and lock variants:
- A286 Flat Washers, DIN 125 (Form A standard) / DIN 9021 (Form B oversize / fender), ISO 7089 / 7093, AN-960 / NAS-620 / MS-15795 in M3-M64 + #4-2".
- A286 Lock Washers, Split-ring (DIN 127), Belleville disc spring (DIN 6796), external-tooth and internal-tooth lock washers (DIN 6797 / 6798).
All A286 washers are stamped or laser-cut from A286 sheet (AMS 5895) or plate (AMS 5525), then solution-treated and aged. Magnetic permeability < 1.005 verified per ASTM A342.
About A286 Washers
TorqBolt produces Alloy A286 (UNS S66286 / DIN 1.4980) washers in plain, lock (split / serrated / external / internal tooth), Belleville disc, fender, structural and shoulder forms from M3 to M64 / #4 to 2-1/2". A286 washers are stamped or machined from AMS 5895 sheet or AMS 5732 bar, solution-treated and aged for use in high-temperature flange joints, jet-engine fasteners, gas-turbine assemblies and any service where 17-7 PH or 304 stainless lose retained-load capability.
A286 Washer Types, Standards & Sizing
Alloy A286 washers are stamped from AMS 5895 sheet (aged) or machined from AMS 5732 bar.
- Plain washer (form A), DIN 125 / ISO 7089 / ASME B18.22.1 type A. OD = 2 × nominal bolt diameter.
- Heavy plain, DIN 7349, thicker (2 × standard) for higher bearing pressure.
- Fender (mudguard), ASME B18.22.1, OD 3-5 × bolt diameter.
- Structural washer, DIN 6916 / ASTM F436, hardened plain washer for ASTM A325 / A490 structural bolt assemblies.
- Split-lock, DIN 127 / ASME B18.21.1 type A. Helical spring-tempered washer.
- Internal-tooth lock, DIN 6797 form J.
- External-tooth lock, DIN 6797 form A.
- Belleville (disc spring), DIN 6796 / DIN 2093. Conical spring washer that retains preload through thermal cycles.
- Wave washer, sinusoidal axial wave; soft preload element.
A286 Belleville Washer Engineering Data
Belleville washers (DIN 2093) are sized by the De-Mees formula relating outside diameter (D), inside diameter (d), thickness (t) and free height (h). For a typical M12 A286 Belleville (D = 25 mm, d = 12.5 mm, t = 1.5 mm, h = 0.5 mm), single-disc free-state deflection produces approximately 4.5 kN spring force at 25 % flat. A286 retains 92 % of room-temperature spring rate at 540 °C and 85 % at 700 °C.
A286 Washer Applications
- Gas-turbine seal-spring stacks, multiple Belleville discs hold seal preload through thermal cycle.
- Jet-engine flange retention, A286 plain washer under bolt head distributes preload onto Inconel mating surface.
- Exhaust manifold and turbocharger waste-gate, A286 split-lock prevents bolt back-off under vibration at 600-700 °C.
Alloy A286 Washers , Specification Overview
An A286 washer’s job is preload retention. Every bolted joint at temperature loses clamp force as the bolt creeps and the joint surfaces relax; an A286 Belleville disc washer compensates by acting as an elastic energy reservoir that pushes the joint back into clamp as relaxation occurs. Stack-design (series for more deflection, parallel for more force) is engineered per joint to deliver constant preload through thousands of thermal cycles.
For non-spring applications, A286 plain and structural washers spread bolt-head load onto soft mating surfaces (titanium engine cases, Inconel turbine wheels) and prevent local crushing or galling. Lock washers, split, internal-tooth, external-tooth, serrated flange , provide vibration-resistant clamp retention.
A286 Washers Governing Standards & Specifications
TorqBolt manufactures every a286 washers to the applicable industry standard. The matrix below lists the principal specifications, material, dimensional, inspection , that a286 washers 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 | F436 / A638 grade 660 | Hardened plain washer; forged stock |
| AMS | 5895 / 5525 / 5732 | Sheet (aged) / sheet (sol-treated) / bar |
| ASME | B18.21.1 / B18.22.1 / B18.21.5 | Lock / plain / structural washer dims |
| DIN | 125 / 7349 / 6916 / 6796 / 2093 / 127 / 6797 / 137 | Metric plain / heavy / structural / Belleville / split / tooth-lock / wave |
| ISO | 7089 / 7090 / 7091 / 7093 / 7094 | Metric plain washers |
| NAS | 1149 / 1587 / 620 | Aerospace flat washer / countersunk / external-tooth |
| MIL-DTL | 1058 / 5045 / 18240 | Aerospace plain / lock / Belleville |
| EN | 10204 3.1 / 3.2 | Mill / third-party cert |
| ASME | PCC-1 | Bolted-joint washer-friction guidelines |
A286 Washers Sizes & Available Patterns
A286 washers are stamped from AMS 5895 sheet (precipitation-aged) or machined from AMS 5732 bar. Belleville disc washers are sized via the De-Mees formula. TorqBolt produces every washer pattern from M3 / #4 to M64 / 2-1/2".
| Pattern | Standard | Metric range | Inch range | Use |
|---|---|---|---|---|
| Plain washer (form A) | DIN 125 / ISO 7089 / ASME B18.22.1 | M3, M64 | #4 , 2-1/2" | Load distribution |
| Heavy plain | DIN 7349 / ASME B18.22.1 type B | M5, M48 | 1/4" , 2" | Heavy-hex bolting |
| Structural (hardened) | ASTM F436 / DIN 6916 | M12, M48 | 1/2" , 2" | A325 / A490 structural bolting |
| Fender (mudguard) | ASME B18.22.1 | M5, M30 | 1/4" , 1-1/4" | Spread load on thin sheet |
| Split-lock | DIN 127 / ASME B18.21.1 | M3, M48 | #4 , 2" | Vibration locking |
| Internal-tooth lock | DIN 6797 form J | M3, M16 | #4 , 5/8" | Soft material lock |
| External-tooth lock | DIN 6797 form A | M3, M16 | #4 , 5/8" | Max locking torque |
| Belleville (disc spring) | DIN 6796 / DIN 2093 | M3, M64 | #4 , 2-1/2" | Preload retention through cycle |
| Wave | DIN 137 | M3, M30 | #4 , 1-1/4" | Soft preload element |
A286 Washers Manufacturing Process
Every a286 washers 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 & sheet rolling: AMS 5895 sheet (aged condition) or AMS 5525 sheet (solution-treated) supplied by a vacuum-melt mill.
- Blanking: washer blanks stamped from sheet on a progressive die. For Belleville and conical forms the blank is dished in a follow-on press operation.
- Trimming & deburring: ID and OD trimmed to drawing tolerances; sharp edges removed by tumble-deburring or vibratory finishing.
- Heat treatment: if blanks were stamped from solution-treated sheet, they are aged at 720 °C / 16 h to develop the precipitation strength.
- Belleville-specific: dishing is performed before aging so the elastic spring rate is set by the aged microstructure, not by cold-work residual stress.
- Surface finish: passivation per ASTM A967, or silver-plate per AMS 2410 for low-friction bearing-face washers.
- Inspection: dimensional gauge (ID / OD / thickness / dish height), hardness, spring-rate test on Belleville samples.
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.
Washer Inspection & Spring-Rate Verification
Plain and lock washers go through dimensional and hardness release per ASTM F436 or DIN 6916. Belleville disc washers add a load-deflection signature test that is unique to A286 spring service:
- Outside diameter, inside diameter, thickness, and dish height gauged per DIN 2093 or NASM 14014.
- Load-deflection curve traced on a sample per lot at 25 % flat compression. Spring rate must fall within ±10 % of the design value.
- Hardness traverse verifying the aging cycle was complete (HV 280 to 320, equivalent to HRC 30-32).
- Bearing-face flatness on plain washers per ASME B18.22.1.
- Salt-spray and passivation verification when the washer ships with a corrosion-protection finish.
- Spring-fatigue spot-check on Belleville lots destined for jet-engine seal service, 10 000 cycles at design deflection without load loss > 5 %.
EN 10204 3.1 covers most industrial work. Aerospace and gas-turbine customers usually invoke type 3.2 plus AS9100D first-article reporting.
A286 Washer Applications by Industry
Gas-turbine seal-spring stacks
Up to 50 individual A286 Belleville discs stacked in series-parallel between a labyrinth-seal carrier and a casing. Maintains seal preload through 540-700 °C cycles for the full inspection interval.
Jet-engine flange retention
Plain A286 washers under each casing-bolt head, distributing preload onto Inconel-718 or titanium mating surfaces without local Brinell yielding.
Turbocharger waste-gate and exhaust manifold
Split-lock or serrated A286 washers on each manifold flange bolt prevent back-off under engine-mount vibration.
Bus-bar electrical connections
A286 conical or Belleville washer maintains contact pressure on bus-bar terminations as copper expands and creeps in service. Non-magnetic property avoids hysteresis losses.
Aerospace fuel-system flanges
Fender washers spread bolt load on aluminium tank bosses; structural washers on fuel-line flange bolts retain torque through flight thermal cycles.
A286 Washers vs Alternative Materials
Washer material choice is dominated by spring-rate retention through thermal cycles. 17-7 PH springs at 315 °C, A286 to 700 °C, Inconel X-750 to 750 °C. Plain F436 alloy washers are the commodity baseline for non-spring service.
| Property | A286 washer | 17-7 PH | Inconel X-750 | F436 alloy |
|---|---|---|---|---|
| Spring-rate retention | 700 °C | 315 °C | 750 °C | 200 °C |
| RT hardness | HRC 30-32 | HRC 38-42 | HRC 34-38 | HRC 38-42 |
| Magnetic | No | Yes | No | Yes |
| Belleville life cycles | 10⁶+ at 540 °C | 10⁶ at 200 °C | 10⁶+ at 700 °C | N/A (plain only) |
| Cost index | 1.0× | 0.4× | 4.0× | 0.2× |
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 Washer
- Material spec: AMS 5895 (sheet, aged) for stamped washers; AMS 5732 (bar, aged) for machined.
- Pattern: plain / heavy plain / structural / fender / split-lock / tooth-lock / Belleville / wave.
- Dimensional standard: DIN 125 / ISO 7089 / DIN 6916 / DIN 2093 / DIN 6796 / DIN 6797 / NAS 1149 / ASME B18.21.1.
- Size: nominal bore (e.g. M16) and form code per the standard.
- Belleville-specific: additionally specify dishing height, OD, ID, thickness, and load-deflection rate.
- Surface finish: passivated, silver-plated, or dry-film lubricated per drawing.
- Inspection certificate: EN 10204 3.1 default, 3.2 if invoked.
Example: “Belleville disc washer, AMS 5895, DIN 2093 size A16, OD 31 mm / ID 16.3 mm / t 1.75 mm / dish 0.85 mm, EN 10204 3.1, spring-rate 4.5 kN at 25 % flat.”
Why TorqBolt for A286 Washers
Plain and lock washers are commodity, but Belleville disc washers and matched spring stacks are where A286 expertise actually matters:
- Belleville design library: standard sizes per DIN 2093 from 6 mm to 250 mm OD; custom load-deflection profiles to drawing.
- Spring-stack engineering: series-parallel stack design for gas-turbine seal-spring service that retains preload through 10,000 thermal cycles.
- Pre-aged stamped sheet stock: AMS 5895 sheet held in inventory for fast-turn plain-washer orders.
30-plus years of fastener manufacture; ISO 9001:2015 + AS9100D + PED 2014/68/EU; spring-rate verification on every Belleville lot per DIN 2093 and AMS 5895; full lot traceability.
A286 Washer Demand
Plain washers ship from inventory; the engineering work is on the Belleville side. Recent Belleville design wins include a 22-disc series-parallel stack for a gas-turbine seal cartridge (designed to retain 8 kN preload through 24,000 thermal cycles), a single-disc M16 spring under exhaust-manifold flange bolts on a Tier 1 truck OEM, and a bus-bar contact-pressure stack for a high-current switchgear manufacturer.
QA observation: about 1 in 30 customer drawings for Belleville stacks gets the series-vs-parallel orientation reversed. The deflection requirement is correct; the load requirement is correct; the stack drawing puts the discs nose-to-nose when it should be nose-to-tail. We catch this at order-review and confirm with the customer's engineer; rebuilds avoided so far in 2024: nine.
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