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GB93-85 Lock Washer 70# Steel Zinc

GB93-85 Helical Spring Lock Washer — 70# Spring Steel, Zinc Plated

FULLERKREG GB93-85 helical spring lock washers are manufactured to GB 93-1987 standard in 70# high-carbon spring steel (Grade 70, per GB/T 699) with mechanical zinc plating. Superior spring force (40–50 HRC), enhanced corrosion resistance, no hydrogen embrittlement risk. Size range M2–M48.

Product Highlights

  • Standard: GB 93-1987
  • Material: 70# Spring Steel (Grade 70, GB/T 699)
  • Surface: Mechanical Zinc Plating (GB/T 17460) — no H2 embrittlement
  • Hardness: 40–50 HRC after quench and temper
  • Size Range: M2–M48
  • RoHS and REACH Compliant

Dimensional Specifications

Per GB 93-1987, all dimensions in mm.

Size d min d max h nom H min H max kg/1000pcs
M2 2.1 2.35 0.5 1.0 1.25 0.016
M2.5 2.6 2.85 0.65 1.3 1.63 0.033
M3 3.1 3.4 0.8 1.6 2.0 0.06
M4 4.1 4.4 1.1 2.2 2.75 0.15
M5 5.1 5.4 1.3 2.6 3.25 0.258
M6 6.1 6.68 1.6 3.2 4.0 0.47
M8 8.1 8.68 2.1 4.2 5.25 1.07
M10 10.2 10.9 2.6 5.2 6.5 2.06
M12 12.2 12.9 3.1 6.2 7.75 3.51
M16 16.2 16.9 4.1 8.2 10.25 8.15
M20 20.2 21.04 5.0 10.0 12.5 15.05
M24 24.5 25.5 6.0 12.0 15.0 26.23
M30 30.5 31.5 7.5 15.0 18.75 51.06
M36 36.5 37.7 9.0 18.0 22.5 88.03
M42 42.5 43.7 10.5 21.0 26.25 139.6
M48 48.5 49.7 12.0 24.0 30.0 208.1

Non-preferred sizes M14, M18, M22, M27, M33, M39, M45 available on request.

Material Properties — 70# Spring Steel (GB/T 699)

Property Value
Grade 70# (C 0.67–0.75%, Mn 0.50–0.80%)
Hardness 40–50 HRC (392–513 HV)
Tensile Strength 1275 MPa min.
Surface Mechanical Zinc Plating, 8–25 um
Temp. Range -40 to +120 C
RoHS/REACH Compliant

Why Mechanical Zinc Plating?

At 40–50 HRC, electroplating introduces hydrogen embrittlement risk. Mechanical zinc plating (tumbling with zinc powder, no acid pickling, no electrical current) eliminates this risk while providing 8–25 um zinc coating for enhanced corrosion protection.

Product Photo Gallery

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Applications

  • Heavy machinery requiring high spring force with corrosion protection
  • Outdoor construction and steel structures
  • Automotive chassis and underbody components
  • Agricultural and mining equipment
  • Railway and transportation assemblies
  • GB-standard bolt assemblies in humid environments

FAQ

Q: Why mechanical zinc not electroplating? At HRC 40+, electroplating causes hydrogen embrittlement. Mechanical plating is safe for high-hardness spring steel.

Q: How does zinc compare to black oxide? Zinc (8–25 um) gives much better corrosion resistance for outdoor/humid use. Black oxide (1–3 um) is for indoor/dry only.

Q: Is 70# the same as 65Mn? No. 70# (GB/T 699): C 0.67–0.75%, Mn 0.50–0.80%. 65Mn (GB/T 1222): C 0.62–0.70%, Mn 0.90–1.20%. Distinct grades.

Q: Non-preferred sizes available? Yes, M14/M18/M22/M27/M33/M39/M45 on request.

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

FULLERKREG Fasteners — Precision GB and DIN Standard Fasteners, Direct from Manufacturer.

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