Home » GB93-85 Lock Washer 65Mn Steel 430-510HV Black

GB93-85 Lock Washer 65Mn Steel 430-510HV Black

GB93-85 Helical Spring Lock Washer — 65Mn Spring Steel, 430–510HV, Black Oxide

FULLERKREG GB93-85 helical spring lock washers are manufactured to GB 93-1987 standard in 65Mn high-manganese spring steel (per GB/T 1222) with a black oxide surface treatment. 65Mn spring steel achieves 430–510 HV hardness after quench and temper, delivering high spring force, excellent elastic recovery, and superior fatigue resistance. Black oxide is the preferred surface treatment for high-hardness spring steel — it produces a uniform magnetite (Fe3O4) conversion coating with no hydrogen introduction, eliminating the embrittlement risk associated with electroplating at this hardness level.

Product Highlights

  • Standard: GB 93-1987
  • Material: 65Mn Spring Steel (GB/T 1222)
  • Surface: Black Oxide (Chemical Blackening) — no hydrogen embrittlement risk
  • Appearance: Uniform matte black, non-reflective finish
  • Hardness: 430–510 HV (approx. 44–50 HRC) after quench and temper
  • Size Range: M2–M48
  • Function: Helical spring lock washer — anti-loosening via spring-back tension and bite-in effect
  • RoHS and REACH Compliant

Dimensional Specifications — GB93 Lock Washers (65Mn Steel, Black Oxide)

Per GB 93-1987, all dimensions in mm.

Size d min d max h nom h min h max H min H max kg/1000pcs
M2 2.1 2.35 0.5 0.42 0.58 1.0 1.25 0.016
M2.5 2.6 2.85 0.65 0.57 0.73 1.3 1.63 0.033
M3 3.1 3.4 0.8 0.7 0.9 1.6 2.0 0.06
M4 4.1 4.4 1.1 1.0 1.2 2.2 2.75 0.15
M5 5.1 5.4 1.3 1.2 1.4 2.6 3.25 0.258
M6 6.1 6.68 1.6 1.5 1.7 3.2 4.0 0.47
M8 8.1 8.68 2.1 2.0 2.2 4.2 5.25 1.07
M10 10.2 10.9 2.6 2.45 2.75 5.2 6.5 2.06
M12 12.2 12.9 3.1 2.95 3.25 6.2 7.75 3.51
(M14) 14.2 14.9 3.6 3.4 3.8 7.2 9.0 5.51
M16 16.2 16.9 4.1 3.9 4.3 8.2 10.25 8.15
(M18) 18.2 19.04 4.5 4.3 4.7 9.0 11.25 10.98
M20 20.2 21.04 5.0 4.8 5.2 10.0 12.5 15.05
(M22) 22.5 23.34 5.5 5.3 5.7 11.0 13.75 20.24
M24 24.5 25.5 6.0 5.8 6.2 12.0 15.0 26.23
(M27) 27.5 28.5 6.8 6.5 7.1 13.6 17.0 37.88
M30 30.5 31.5 7.5 7.2 7.8 15.0 18.75 51.06
(M33) 33.5 34.7 8.5 8.2 8.8 17.0 21.25 72.43
M36 36.5 37.7 9.0 8.7 9.3 18.0 22.5 88.03
(M39) 39.5 40.7 10.0 9.7 10.3 20.0 25.0 118.2
M42 42.5 43.7 10.5 10.2 10.8 21.0 26.25 139.6
(M45) 45.5 46.7 11.0 10.7 11.3 22.0 27.5 163.4
M48 48.5 49.7 12.0 11.7 12.3 24.0 30.0 208.1

Sizes in parentheses are non-preferred per GB93, available on request. Weights based on steel density 7.85 g/cm3.

Material Properties — 65Mn Spring Steel

Property Value
Material Grade 65Mn Spring Steel
GB Standard GB/T 1222, GB/T 4354
Heat Treatment Quench and Temper
Hardness 430–510 HV (approx. 44–50 HRC)
Tensile Strength 1275 MPa min. (after HT)
Surface Treatment Black Oxide (Chemical Blackening / Fe3O4)
Coating Thickness 1–3 um (conversion coating, no dimensional impact)
Operating Temperature -40 to +120 C
RoHS / REACH Compliant

Chemical Composition — 65Mn Spring Steel (GB/T 1222)

Element C Mn Si P max S max Cr max Ni max
Content % 0.62–0.70 0.90–1.20 0.17–0.37 0.035 0.035 0.25 0.25

65Mn has higher manganese (0.90-1.20%) than 70# steel (0.50-0.80%), improving hardenability and toughness for larger cross-sections.

Black Oxide Surface Treatment

Black oxide (chemical blackening) produces a uniform Fe3O4 magnetite conversion coating through an alkaline oxidizing bath. Key advantages for high-hardness spring steel:

  • No hydrogen embrittlement — no acid pickling, no electrical current, safe at 430-510 HV
  • Negligible coating thickness (1-3 um) — zero impact on spring tolerances or dimensions
  • Uniform matte black finish — professional, non-reflective appearance
  • RoHS compliant — no heavy metals or restricted substances
  • Basic corrosion inhibition — apply oil or wax for outdoor/humid environments

Black Oxide vs. Zinc — Comparison

Property Black Oxide Zinc (Mechanical)
Coating thickness 1–3 um 8–25 um
Corrosion resistance Basic — indoor / dry Good — light outdoor and humid
H2 embrittlement risk None None (mechanical process)
Appearance Matte black Bright silver-grey
Dimensional impact Negligible 8–25 um added
Best for Indoor, dry, precision assemblies Outdoor, humid, general industrial

Product Photo Gallery

FULLERKREG GB93-85 Lock Washer, 65Mn Spring Steel, Black Oxide:

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

Application Scenarios

  • Heavy machinery and industrial equipment — indoor or dry environments
  • Automotive manufacturing — engine, chassis, and drivetrain assemblies
  • Electrical enclosures and control panels — non-reflective black finish preferred
  • Precision mechanical assemblies — negligible coating thickness preserves tolerances
  • Railway and transportation equipment in sheltered environments
  • GB-standard bolt assemblies requiring high spring force and anti-loosening

Elastic Test Load — GB 9/T94.1-2008

Size M2 M3 M4 M5 M6 M8 M10 M12 M16 M20 M24 M30 M36 M42 M48
Load (N) 700 1760 3050 5050 7050 12900 20600 30000 56300 88000 127000 204000 298000 394000 518000

FAQ

Q: What is 65Mn spring steel? 65Mn (GB/T 1222) is a high-manganese spring steel with C 0.62-0.70% and Mn 0.90-1.20%. The high Mn content improves hardenability and toughness. After quench and temper, it achieves 430-510 HV, providing excellent spring force and fatigue resistance for lock washers.

Q: Why black oxide for 65Mn spring steel? At 430-510 HV, electroplating introduces hydrogen embrittlement risk. Black oxide is a chemical conversion coating with no acid pickling and no electrical current, eliminating this risk. It is the preferred finish for high-hardness spring steel in dry/indoor environments.

Q: When to choose black oxide vs. zinc? Black oxide is ideal for indoor, dry, or precision applications where dimensional change must be minimized (1-3 um coating). Choose zinc plating for outdoor or humid environments requiring better corrosion protection (8-25 um coating).

Q: Non-preferred sizes available? Yes. M14, M18, M22, M27, M33, M39, M45 available 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. Contact our sales team for wholesale inquiries and custom orders.

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