Home » DIN 137A Spring Washer (Curved) – 65Mn Steel Zinc CR3

DIN 137A Spring Washer (Curved) – 65Mn Steel Zinc CR3

DIN 137A Curved Spring Washer — 65Mn Spring Steel, Zinc Plated CR3

FULLERKREG DIN 137A curved spring washers are manufactured to DIN 137 Type A standard in 65Mn high-manganese spring steel (per GB/T 1222) with zinc electroplating and trivalent chromium (CR3) passivation. DIN 137 Type A is a curved (dished) spring washer with a larger outer diameter than DIN 128A, providing greater spring travel and higher load capacity for the same bolt size. 65Mn spring steel achieves 430–510 HV hardness after quench and temper. The zinc CR3 finish provides ≥72h salt spray resistance with full RoHS compliance — no hexavalent chromium.

Note on hydrogen embrittlement: At 430–510 HV, electroplating introduces hydrogen embrittlement risk. FULLERKREG applies mandatory post-plate baking (per ISO 9587 / GB/T 13912) to eliminate this risk.

Product Highlights

  • Standard: DIN 137 Type A (Curved Spring Washer)
  • Material: 65Mn Spring Steel (GB/T 1222)
  • Surface Treatment: Zinc Electroplating + CR3 Trivalent Chromium Passivation
  • Corrosion Resistance: ≥72h NSS per ISO 9227
  • Hardness: 430–510 HV (approx. 44–50 HRC) after quench & temper
  • Size Range: M3 – M36
  • Profile: Type A — Curved / dished (larger OD than DIN 128A, greater spring travel)
  • RoHS Compliant — CR3, no Cr6+
  • Post-plate baking — hydrogen embrittlement relief per ISO 9587

Dimensional Specifications — DIN 137 Type A (Curved), 65Mn Steel Zinc CR3

All dimensions in mm. Per DIN 137 Type A.

Nominal Size For Bolt d1 min d2 max h min h max s (thickness)
3 M3 3.2 7.5 0.8 1.2 0.5
4 M4 4.3 9.5 1.0 1.4 0.6
5 M5 5.3 11.5 1.2 1.7 0.8
6 M6 6.4 14.0 1.5 2.1 1.0
8 M8 8.4 18.0 2.0 2.8 1.2
10 M10 10.5 22.0 2.5 3.5 1.5
12 M12 13.0 26.0 3.0 4.2 1.8
14 M14 15.0 30.0 3.5 4.9 2.0
16 M16 17.0 34.0 4.0 5.6 2.5
20 M20 21.0 42.0 5.0 7.0 3.0
24 M24 25.0 50.0 6.0 8.4 3.5
30 M30 31.0 62.0 7.5 10.5 4.0
36 M36 37.0 74.0 9.0 12.6 5.0

Material Properties — 65Mn Spring Steel (GB/T 1222)

Property Value
Material Grade 65Mn Spring Steel
C Content 0.62 – 0.70%
Mn Content 0.90 – 1.20%
Hardness 430–510 HV (44–50 HRC)
Tensile Strength 1275 MPa min.
Surface Zinc CR3, 5–12 um, ≥72h NSS
H2 Embrittlement Post-plate baking per ISO 9587
RoHS / REACH Compliant — CR3, no Cr6+

DIN 137A vs. DIN 137B

Feature Type A (Curved) Type B (Crinkled)
Profile Single curved arc Multiple corrugations
Contact Continuous curved Multi-point
Best for High load, smooth bearing surface General assemblies

Application Scenarios

  • High-load bolted assemblies — larger OD vs. DIN 128A, greater spring travel
  • Heavy machinery & industrial equipment — outdoor corrosion protection
  • Automotive — chassis and underbody exposed to moisture
  • Construction & steel structures — sheltered outdoor environments
  • Agricultural & mining equipment — high-vibration, humid conditions
  • Soft material assemblies — no sharp edges, no surface marking

Product Photo Gallery

FULLERKREG DIN 137A Curved Spring Washer, 65Mn Spring Steel, Zinc CR3:

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

Why Choose FULLERKREG?

  • 🏭 Direct manufacturer — factory in China, no middlemen
  • 📐 Strict DIN dimensional control — 100% inspection on critical dimensions and hardness
  • 🌍 Global export experience — Europe, North America, Southeast Asia
  • 📦 Flexible MOQ — trial orders and bulk shipments welcome
  • 📋 Full documentation — mill certs, hardness reports, salt spray reports, RoHS declarations
  • ⚡ Fast lead times — standard sizes in stock

FAQ

Q: What is CR3 passivation?
A: Trivalent chromium passivation over zinc electroplating. Provides ≥72h NSS corrosion protection without Cr6+. Fully RoHS compliant.

Q: How is hydrogen embrittlement managed?
A: Post-plate baking at 190–220°C for 4–8 hours per ISO 9587 drives off absorbed hydrogen before the zinc coating seals.

Q: DIN 137A vs. DIN 128A?
A: DIN 137A has larger OD and greater spring travel for the same bolt size. DIN 128A is designed for cheese head and pan head screws with smaller OD.

Q: Certificates available?
A: Yes. Mill certs, hardness reports, salt spray reports, RoHS declarations on request.

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

Sorry, this collection is empty.
Continue shopping