Home » GB93-85 Lock Washer 70# Steel Black

GB93-85 Lock Washer 70# Steel Black

GB93-85 Helical Spring Lock Washer — 70# Spring Steel, Black Oxide

FULLERKREG GB93-85 helical spring lock washers are manufactured to GB 93-1987 standard in 70# high-carbon spring steel (Grade 70, equivalent to 65Mn or 70 carbon steel per GB/T 4354 / GB/T 1222) with a black oxide surface treatment. The 70# spring steel grade delivers superior spring force, higher hardness (40–50 HRC), and greater fatigue resistance compared to standard carbon steel, making these washers the preferred choice for heavy-duty machinery, high-vibration assemblies, and structural applications. The black oxide finish provides a uniform matte-black appearance with basic corrosion inhibition.

Product Highlights

  • Standard: GB 93-1987
  • Material: 70# High-Carbon Spring Steel (Grade 70 / 65Mn, per GB/T 4354 & GB/T 1222)
  • Surface Treatment: Black Oxide (Chemical Blackening / Gun-Black)
  • Appearance: Uniform matte black, non-reflective finish
  • Hardness: 40 – 50 HRC (392 – 513 HV) after quench & temper
  • Size Range: M2 – M48
  • Function: Helical spring lock washer — high spring force, anti-loosening under heavy vibration
  • RoHS & REACH Compliant

Dimensional Specifications — GB93 Lock Washers (70# Steel, Black Oxide)

All dimensions in millimeters (mm). Per GB 93-1987.

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

* Sizes in parentheses ( ) are non-preferred sizes per GB93. Weight values based on steel density ≈7.85 g/cm³. Please verify with your engineering team for critical applications.

Elastic Test Free Height — GB 9/T94.1-2008 Table 2

Minimum free height after elastic test (mm):

Size M3 M4 M5 M6 M8 M10 M12 M14 M16 M18 M20 M22 M24 M27 M30
Free height ≥ (mm) 0.9 1.0 1.25 1.6 2.1 2.4 2.8 3.2 3.8 3.8 4.4 4.4 5.6 5.6 8.0

Elastic Test Load — GB 9/T94.1-2008 Table 3

Minimum elastic test load (N):

Size (mm) M2 M2.5 M3 M4 M5 M6 M8 M10 M12 M14 M16 M18 M20 M22 M24 M27 M30 M33 M36 M39 M42 M45 M48
Test Load (N) 700 1,160 1,760 3,050 5,050 7,050 12,900 20,600 30,000 41,300 56,300 69,000 88,000 110,000 127,000 167,000 204,000 255,000 298,000 343,000 394,000 457,000 518,000

Material & Mechanical Properties — 70# High-Carbon Spring Steel

Property Value
Material Grade 70# Spring Steel (Grade 70 / 65Mn)
GB Standard Reference GB/T 4354, GB/T 1222, GB/T 5222
Heat Treatment Quench & Temper (淬火并回火)
Hardness 40 – 50 HRC (392 – 513 HV)
Tensile Strength (Rm) ≥ 1,275 MPa (typical for 65Mn spring steel)
Yield Strength (Rp0.2) ≥ 1,175 MPa
Elongation ≥ 8%
Surface Treatment Black Oxide (Chemical Blackening)
Coating Thickness 1 – 3 μm (conversion coating, no dimensional impact)
Operating Temperature -40°C to +120°C
RoHS / REACH Compliant

Chemical Composition — 70# Spring Steel (65Mn)

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

Surface Treatment — Black Oxide Explained

Black oxide (chemical blackening / gun-black) is a chemical conversion coating applied through an alkaline oxidizing bath, producing a uniform magnetite (Fe₃O₄) layer on the steel surface. Key characteristics for spring washers:

  • ✅ Uniform matte black finish — professional appearance, non-reflective
  • ✅ Negligible dimensional change — coating only 1–3 μm, zero impact on spring tolerances
  • ✅ No hydrogen embrittlement risk — unlike electroplating, black oxide does not introduce hydrogen into high-hardness spring steel
  • ✅ RoHS compliant — no heavy metals or hazardous substances
  • ⚠️ Moderate corrosion resistance — apply oil or wax sealant for outdoor or humid environments
  • ✅ Preferred finish for high-hardness spring steel — avoids hydrogen embrittlement risk associated with electroplating at HRC ≥40

70# Spring Steel vs. Standard Carbon Steel — Key Differences

Property 70# Spring Steel (65Mn) Low Carbon Steel
Carbon content 0.62 – 0.70% ≤ 0.20%
Hardness after HT 40 – 50 HRC (392–513 HV) 100 – 200 HV
Tensile strength ≥ 1,275 MPa ≥ 300 MPa
Spring force High — superior elastic recovery Low
Fatigue resistance Excellent Standard
Recommended application Heavy machinery, high-vibration, structural Light assembly, general use
Surface treatment Black oxide (avoids H₂ embrittlement) Zinc plating, black oxide

GB93 vs. DIN 127 — Key Differences

Feature GB 93-1987 DIN 127 Type B
Origin Chinese national standard German DIN standard
Size range M2 – M48 M2 – M80
Dimensional compatibility Largely compatible with DIN 127B for common sizes International reference standard
Common use region China domestic & export to Asia Europe, global industrial
Technical standard GB 9/T94.1-2008 DIN 127 / ISO 3506

How GB93 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 hardened edges (40–50 HRC) bite deeply into both the bearing surface and the nut/bolt head, providing superior grip vs. soft steel washers
  • Anti-loosening: High spring force from 70# steel resists loosening under heavy vibration and dynamic loads
  • Pre-tension: Provides initial pre-tension to maintain connection stability in both static and dynamic conditions

Application Scenarios

  • Heavy machinery & industrial equipment — high spring force and hardness for demanding vibration environments
  • Automotive manufacturing — engine assemblies, chassis, suspension, and drivetrain components
  • Construction & steel structures — structural bolted connections requiring reliable anti-loosening
  • Railway & transportation equipment — high-vibration track and rolling stock assemblies
  • Mining & heavy industry — extreme vibration and shock load environments
  • HVAC & mechanical systems — equipment mounting in vibration-prone installations
  • GB-standard bolt assemblies — standard spring washer for GB-standard heavy-duty bolt assemblies

Product Photo Gallery

Real product images — FULLERKREG GB93-85 Lock Washer, 70# Spring Steel, Black Oxide:

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

Packaging & Supply

Size Standard Pack (pcs) Bulk Carton (pcs) Weight per 1000 pcs (approx.)
M3 200 10,000 ~60 g
M4 200 5,000 ~150 g
M5 100 3,000 ~258 g
M6 100 2,000 ~470 g
M8 50 1,000 ~1,070 g
M10 50 500 ~2,060 g
M12 25 500 ~3,510 g
M16 25 200 ~8,150 g
M20 10 100 ~15,050 g
M24 10 50 ~26,230 g

Sizes M27–M48 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 GB dimensional control — 100% inspection on critical dimensions and hardness
  • 🌍 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, hardness test reports, RoHS declarations available
  • ⚡ Fast lead times — standard sizes in stock, ready to ship

Frequently Asked Questions

Q: What is 70# spring steel and why is it used for lock washers?
A: 70# spring steel (Grade 70, equivalent to 65Mn) is a high-carbon manganese spring steel with a carbon content of 0.62–0.70%. After quench and temper heat treatment, it achieves 40–50 HRC hardness, providing superior spring force, elastic recovery, and fatigue resistance compared to standard carbon steel. This makes it the preferred material for heavy-duty spring lock washers.

Q: Why is black oxide used instead of zinc plating for 70# spring steel?
A: At hardness levels of 40–50 HRC, electroplating processes (including zinc plating) can introduce hydrogen into the steel, causing hydrogen embrittlement and potential brittle fracture. Black oxide is a chemical conversion coating that does not introduce hydrogen, making it the safe and preferred surface treatment for high-hardness spring steel fasteners.

Q: What is GB93 and how does it relate to DIN 127?
A: GB 93-1987 is the Chinese national standard for helical spring lock washers, equivalent in function to DIN 127 Type B. For common sizes (M2–M48), the dimensions are largely compatible. GB93 is the standard specification for spring washers used in GB-standard bolt assemblies in China.

Q: Is black oxide suitable for outdoor use?
A: Black oxide provides basic corrosion inhibition. For outdoor or humid environments, apply a light oil or wax sealant after installation. For corrosive environments, consider stainless steel grades (A2 or A4).

Q: Are sizes in parentheses available?
A: Yes. Sizes shown in parentheses (e.g. M14, M18, M22) are non-preferred sizes per GB93 but are available upon request. Please contact FULLERKREG for availability and lead times.

Q: Are these washers RoHS compliant?
A: Yes. FULLERKREG 70# spring steel black oxide 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, hardness test reports, chemical composition reports, and dimensional inspection reports are available for all orders upon request.

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

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