DIN 436 Square Washer for Wood Construction — A4 Marine Stainless Steel (SUS316), Whitened & Passivated

FULLERKREG DIN 436 square flat washers are manufactured to DIN 436 standard in A4 marine stainless steel (SUS316 / 1.4401 / 06Cr17Ni12Mo2) with a whitened and passivated surface finish. DIN 436 square washers feature a large square external shape providing a significantly larger bearing area than conventional round washers — essential for wood construction, timber framing, and seismic applications where pull-through resistance is critical. A4 stainless steel contains 2–3% molybdenum, providing superior resistance to chloride corrosion, seawater, and acidic environments — the correct choice for marine timber structures, coastal construction, and highly aggressive outdoor environments where A2 (SUS304) may suffer pitting corrosion.

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Product Highlights

• Standard: DIN 436 (Square Flat Washer for Wood Construction)
• Material: A4 Marine Stainless Steel (SUS316 / 1.4401 / 06Cr17Ni12Mo2)
• Surface Treatment: Whitened & Passivated
• Size Range: M10 – M52
• Profile: Square — large bearing area, prevents rotation, distributes load over wide surface
• Molybdenum content: 2–3% — superior chloride & seawater resistance vs. A2
• Primary use: Marine timber structures, coastal construction, seismic applications
• Non-magnetic, non-sparking
• RoHS & REACH Compliant

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Dimensional Specifications — DIN 436 Square Washer, A4 Stainless

All dimensions in millimeters (mm). Per DIN 436. Same dimensions as A2 grade — material and corrosion resistance differ.

For Thread	d1 min	d1 max	a nom	a min	a max	h nom	h min	h max
M10	11	11.43	30	28.7	30	3	2.4	3.6
M12	13	13.5	40	38.4	40	4	3.4	4.6
M16	17.5	18.2	50	48.4	50	4	3.4	4.6
M20	22	22.84	60	58.1	60	4	3.4	4.6
M22	24	24.84	70	68.1	70	5	4	5
M24	26	26.84	80	78.1	80	5	4	5
M27	30	30.84	90	87.8	90	5	4	5
M30	33	34	95	92.8	95	6	5	6.8
M33	36	37	100	97.8	100	6	5	6.8
M36	39	40	110	107.8	110	6	5	6.8
M39	42	43	120	117.5	120	8	6.8	8
M42	45	46	130	127.5	130	8	6.8	8
M45	48	49	140	137.5	140	8	6.8	8
M48	52	53.2	150	147.5	150	8	6.8	8.8
M52	56	57.2	160	157.5	160	10	8.8	11.2

All dimensions in mm per DIN 436. d1 = inner hole diameter; a = square side length; h = washer thickness.

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A4 vs. A2 Stainless Steel — Key Differences

Property	A4 (SUS316) — This Product	A2 (SUS304)
Molybdenum (Mo)	2.0 – 3.0%	None
Chloride resistance	Superior — marine grade	Good — general use
Seawater resistance	Excellent	Limited
Acid resistance	Better (Mo addition)	Standard
Typical use	Marine, offshore, coastal, chemical	General outdoor, food, fresh water

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DIN 436 Square Washer vs. Standard Round Washer

Feature	DIN 436 (Square)	Standard Round Washer (DIN 125)
Shape	Square	Round
Bearing area	Much larger — full square surface	Standard annular area
Pull-through resistance	High — ideal for timber	Standard
Rotation prevention	Yes — square profile locks in timber grain	No
Primary use	Wood construction, timber framing, structural	General bolted assemblies

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Material & Mechanical Properties — A4 Marine Stainless Steel (SUS316)

Property	Value
Material Grade	A4 / SUS316 / 1.4401 / 06Cr17Ni12Mo2
Cr Content	16.0 – 18.0%
Ni Content	10.0 – 14.0%
Mo Content	2.0 – 3.0%
Surface Treatment	Whitened & Passivated
Magnetic	Non-magnetic (austenitic)
Operating Temperature	-196°C to +300°C
Corrosion Resistance	Excellent — seawater, chlorides, acids, marine environments
RoHS / REACH	Compliant

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Application Scenarios

• Marine timber structures — boat docks, jetties, boardwalks in seawater splash zones
• Coastal construction — salt air environments, coastal bridges, waterfront structures
• Seismic-resistant timber construction — DIN 436 designed for seismic applications

Outdoor timber structures in aggressive environments

• — where A2 may suffer chloride pitting
• Swimming pool & water treatment facilities — chlorinated water resistance
• Glulam & engineered timber connections — structural bolting in marine-adjacent locations
• Chemical processing facilities — resistance to acids and chloride-containing media

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Product Photo Gallery

FULLERKREG DIN 436 Square Washer, A4 Marine Stainless Steel:

[ Photo 1 ]

[ Photo 2 ]

[ Photo 3 ]

[ Photo 4 ]

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Why Choose FULLERKREG?

• 🏭 Direct manufacturer — factory in China, no middlemen
• 📐 Strict DIN dimensional control — 100% inspection on critical dimensions
• 🌍 Global export experience — serving distributors in Europe, North America, Southeast Asia
• 📦 Flexible MOQ — small trial orders and large bulk shipments both welcome
• 📋 Full documentation — material certs, RoHS declarations, test reports available
• ⚡ Fast lead times — standard sizes in stock, ready to ship

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Frequently Asked Questions

Q: Why choose A4 over A2 for marine timber construction?
A: A4 (SUS316) contains 2–3% molybdenum which significantly improves resistance to chloride pitting and crevice corrosion. In seawater, coastal, or chloride-rich environments, A4 is the correct choice where A2 (SUS304) may suffer pitting over time.

Q: What is DIN 436?
A: DIN 436 specifies square flat washers for wood construction. The large square profile provides a much greater bearing area than standard round washers, preventing bolt head pull-through in timber and distributing load over a wider surface. Specifically designed for timber framing and seismic applications.

Q: What size range does DIN 436 cover?
A: DIN 436 covers M10 through M52, with square side lengths from 30mm (M10) to 160mm (M52) and thicknesses from 3mm to 10mm.

Q: Do you provide material test certificates?
A: Yes. Mill certificates, chemical composition reports, and dimensional inspection reports are available upon request.

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