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DIN 127 Lock Washer A4 Stainless

DIN 127 Type B Helical Spring Lock Washer — A4 Marine Stainless Steel (SUS316), Whitened & Passivated

FULLERKREG DIN 127 Type B helical spring lock washers are manufactured to DIN 127 standard in A4 marine-grade stainless steel (SUS316 / 1.4401) with a whitened and passivated surface finish. The split helical design creates a spring-like action that resists loosening caused by vibration and dynamic loads. A4 stainless steel adds 2–3% molybdenum to the A2 (SUS304) composition, delivering significantly enhanced resistance to chloride corrosion, seawater, and aggressive chemical environments — the preferred choice for marine, offshore, coastal, and chemical processing applications where A2 is insufficient.

Product Highlights

  • Standard: DIN 127 Type B
  • Material: A4 Marine Stainless Steel (SUS316 / 1.4401)
  • Surface Treatment: Whitened & Passivated (bright silver, uniform stainless finish)
  • Size Range: M2 – M80
  • Function: Helical spring lock washer — resists vibration loosening via spring-back tension and bite-in effect
  • Key advantage over A2: Molybdenum addition (2–3%) — superior chloride, seawater & acid resistance
  • Non-magnetic (austenitic), non-sparking
  • RoHS & REACH Compliant

Dimensional Specifications — DIN 127 Type B Lock Washers (A4 Stainless, Whitened & Passivated)

All dimensions in millimeters (mm). Tolerances per DIN 127.

Nominal Size (d) d1 (min) D (max) B (mm) S / H (mm) H min (mm) Weight (kg/100pcs)
M2 2.1 4.4 1.2 0.5 1.0 0.05
M2.5 2.6 5.1 1.5 0.6 1.2 0.09
M3 3.1 6.2 1.8 0.8 1.6 0.11
M3.5 3.6 7.2 2.0 0.9 1.8 0.18
M4 4.1 7.9 2.3 1.0 2.0 0.24
M5 5.1 9.8 2.8 1.2 2.4 0.46
M6 6.1 11.8 3.3 1.6 3.2 0.83
M8 8.1 15.1 4.1 2.0 4.0 1.8
M10 10.2 18.1 4.9 2.5 5.0 3.4
M12 12.2 21.1 5.8 3.0 6.0 5.67
M14 14.2 24.1 6.5 3.5 7.0 8.72
M16 16.2 27.4 7.5 4.0 8.0 14.2
M18 18.2 29.4 7.5 4.0 8.0 15.7
M20 20.2 33.6 8.5 5.0 10.0 29.2
M22 22.5 35.9 8.5 5.0 10.0 32.0
M24 24.5 40.0 10.0 6.0 12.0 56.2
M27 27.5 44.0 10.0 6.0 12.0 66.0
M30 30.5 48.2 11.0 6.0 12.0 82.0
M33 33.5 52.2 11.0 6.0 12.0 95.0
M36 36.5 57.2 12.0 7.0 14.0 147
M39 39.5 62.2 12.0 7.0 14.0 171
M42 42.5 67.2 13.0 8.0 16.0 253
M45 45.5 71.2 13.0 8.0 16.0 282
M48 48.5 75.2 14.0 8.0 16.0 325
M52 52.5 82.2 15.0 9.0 18.0 490
M56 56.5 87.2 15.0 9.0 18.0 540
M60 60.5 92.2 16.0 10.0 20.0 730
M64 64.5 98.2 16.0 10.0 20.0 810
M68 68.5 104.2 18.0 10.0 20.0 1,020
M72 72.5 109.2 18.0 10.0 20.0 1,110
M76 76.5 115.2 18.0 11.0 22.0 1,370
M80 80.5 121.2 20.0 11.0 22.0 1,770

* All dimensions conform to DIN 127 Type B. Please verify with your engineering team for critical applications.

Material & Mechanical Properties — A4 Stainless Steel (SUS316)

Property Value
Material Grade A4 / SUS316 / 1.4401
Steel Group Austenitic
Strength Class A4-50 / A4-70 / A4-80
Tensile Strength (Rm) ≥ 500 MPa (Class 50)  /  ≥ 700 MPa (Class 70)  /  ≥ 800 MPa (Class 80)
Hardness (HV) ≤ 250 HV (Class 50/70)  /  ≤ 330 HV (Class 80)
Density 7.98 g/cm³
Molybdenum (Mo) Content 2.0 – 3.0% — key differentiator vs. A2
Magnetic Non-magnetic (austenitic)
Operating Temperature -196°C to +400°C
RoHS / REACH Compliant

Per DIN EN ISO 3506-1. Standard supply: A4-70.

Chemical Composition — A4 Stainless Steel (SUS316 / 1.4401)

Element C (max) Cr Ni Mo Mn (max) Si (max) P (max) S (max)
Content (%) 0.07 16.5 – 18.5 10.5 – 13.5 2.0 – 3.0 2.0 1.0 0.045 0.030

A4 Stainless Steel — Property Strength Classes

Steel Group Grade Strength Class Made From Characteristics
Austenitic A4 50 A3, A4 Soft annealed; tensile strength ≥ 500 MPa; dia. ≤ M39
A4 70 A3, A4 Cold worked, normal strength; tensile strength ≥ 700 MPa; dia. ≤ M39
A4 80 AC, AF Extreme cold worked, high strength; tensile strength ≥ 800 MPa; dia. ≤ M20

A4 vs. A2 Stainless Steel — Key Differences

Property A4 (SUS316) A2 (SUS304)
Molybdenum (Mo) 2.0 – 3.0% None
Chloride resistance Excellent — seawater & coastal Good — atmospheric only
Acid resistance Superior (sulfuric, phosphoric) Moderate
Pitting resistance High (Mo inhibits pitting) Standard
Max strength class A4-80 A2-70
Recommended environment Marine, offshore, chemical, food General outdoor, fresh water
Cost Higher (Mo premium) Standard

How DIN 127 Lock Washers Work

  • Spring-back tension: The helical split creates a spring that maintains clamp load as the joint settles, compensating for relaxation and embedding losses
  • Bite-in effect: The sharp edges at the split ends bite into both the bearing surface and the nut/bolt head, resisting rotational loosening under vibration
  • Type B advantage: Greater width (B dimension) and thickness (S) vs. Type A — higher spring force and load capacity for demanding applications

Application Scenarios

  • Marine & offshore structures — hulls, decks, docks, offshore platforms exposed to seawater
  • Coastal & waterfront architecture — railings, facades, bridges in salt-air environments
  • Chemical processing plants — resistance to sulfuric acid, phosphoric acid, and chloride solutions
  • Food & beverage processing — hygienic, easy to clean, no contamination risk
  • Pharmaceutical & medical equipment — high purity, corrosion-free surfaces required
  • Swimming pools & water treatment — chlorinated water resistance
  • HVAC & piping systems — vibration-prone assemblies in corrosive environments
  • Heavy machinery — wherever vibration loosening and corrosion resistance are both critical

Product Photo Gallery

Real product images — FULLERKREG DIN 127 Type B Lock Washer, A4 Marine Stainless Steel:

[ Photo 1 ] [ Photo 2 ] [ Photo 3 ] [ Photo 4 ]

Packaging & Supply

Size Standard Pack (pcs) Bulk Carton (pcs) Weight per 100 pcs (approx.)
M3 200 10,000 ~11 g
M4 200 5,000 ~24 g
M5 100 3,000 ~46 g
M6 100 2,000 ~83 g
M8 50 1,000 ~180 g
M10 50 500 ~340 g
M12 25 500 ~567 g
M16 25 200 ~1,420 g
M20 10 100 ~2,920 g
M24 10 50 ~5,620 g

Sizes M27–M80 available upon request. Custom packaging and labeling available for OEM / wholesale orders. Contact FULLERKREG for bulk pricing.

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

Frequently Asked Questions

Q: What is the main advantage of A4 over A2 for lock washers?
A: A4 (SUS316) contains 2–3% molybdenum, which significantly enhances resistance to chloride pitting, seawater corrosion, and aggressive acids. For marine, coastal, chemical, or pool environments, A4 is the correct choice where A2 would be susceptible to pitting or crevice corrosion.

Q: What is the difference between DIN 127 Type A and Type B?
A: Type B (standard type) has a larger outer diameter and greater width (B dimension) than Type A, resulting in higher spring force and load capacity. FULLERKREG supplies Type B as standard.

Q: How does a helical spring lock washer prevent loosening?
A: The split helical design creates spring-back tension that maintains clamp load as the joint settles. The sharp edges at the split ends also bite into the bearing surface and fastener, resisting rotational loosening under vibration and dynamic loads.

Q: Is A4 stainless suitable for full seawater immersion?
A: A4 (SUS316) performs well in seawater splash zones and salt-air environments. For continuous full immersion in seawater under high stress, super duplex or higher-grade alloys may be considered for critical structural applications.

Q: What strength class are these lock washers supplied in?
A: Standard supply is A4-70. A4-50 and A4-80 are available upon request. Please specify your required strength class when ordering.

Q: Are these washers RoHS compliant?
A: Yes. FULLERKREG A4 stainless steel lock washers are fully RoHS and REACH compliant. Compliance documentation is available upon request.

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

FULLERKREG Fasteners — Precision DIN Standard Fasteners, Direct from Manufacturer.
For wholesale inquiries, technical questions, or custom orders, please contact our sales team.

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