Home » Full Thread Hex Bolts (DIN 933) - Bright Zinc Plated High Tensile Steel (8.8)

Full Thread Hex Bolts (DIN 933) - Bright Zinc Plated High Tensile Steel (8.8)

Full Thread Hex Bolts (DIN 933 / GB 5783) — Bright Zinc Plated CR3 High Tensile Steel Grade 8.8

FULLERKREG DIN 933 / GB 5783 Grade 8.8 full thread hex bolts with bright zinc plating (Zinc CR3) combine reliable structural strength with a bright, attractive silver finish and RoHS-compliant corrosion protection. Manufactured from 10B21 or 35K medium carbon steel and electroplated with zinc followed by trivalent chromate (CR3) passivation per ISO 4042, these bolts are the most widely used general-purpose structural fastener in manufacturing, construction, and industrial assembly worldwide. The fully threaded shank ensures maximum thread engagement and grip-length flexibility. Compliant with DIN 933, GB 5783, and ISO 4017 standards.

Product Highlights

  • Brand: FULLERKREG
  • Standards: DIN 933 / GB 5783 / ISO 4017
  • Material: 10B21 or 35K Medium Carbon Steel
  • Property Class: Grade 8.8 (per ISO 898-1 / DIN EN ISO 898-1)
  • Thread Type: Full Thread (Fully Threaded Shank)
  • Surface Treatment: Bright Zinc Plated + CR3 Trivalent Chromate Passivation (Zinc CR3)
  • Zinc Layer Thickness: 5–12 μm (per ISO 4042)
  • RoHS Compliance: Yes — CR3 trivalent chromium, hexavalent chromium-free
  • Head Type: Hexagon (Hex Head)
  • Size Range: M3 – M24
  • Thread: Metric coarse thread per ISO 261 / DIN 13
  • Appearance: Bright silver / light iridescent finish

Why Choose FULLERKREG DIN 933 Grade 8.8 Bright Zinc CR3 Hex Bolts?

  • ✅ Grade 8.8 structural strength — Rm ≥ 800 MPa; the global standard structural bolt grade for general industrial and construction applications
  • ✅ Zinc CR3 — RoHS compliant — trivalent chromate (CR3) replaces hazardous hexavalent chromium (CR6), meeting EU RoHS and REACH directives
  • ✅ Bright attractive finish — uniform bright silver appearance suitable for visible fastening applications
  • ✅ Good corrosion resistance — ≥ 72 hours white rust resistance per ISO 9227 salt spray test
  • ✅ Minimal dimensional impact — thin 5–12 μm coating maintains thread tolerances; standard nuts fit without modification
  • ✅ 10B21 / 35K steel — boron-alloyed or medium carbon steel with excellent cold heading and hardenability characteristics
  • ✅ Full thread design — maximum thread engagement; ideal for through-bolting and variable grip-length applications
  • ✅ Cost-effective — optimal performance-to-cost ratio for general industrial and construction applications
  • ✅ Wholesale & bulk supply — available in large quantities for distributors, OEMs, and contractors

Zinc CR3 Surface Treatment — Properties & Benefits

Property Details
Process Electrolytic zinc plating + trivalent chromate (CR3) passivation
Chromium Type CR3 — Trivalent Chromium (Cr³⁺) — RoHS compliant
Appearance Bright silver / light iridescent finish
Zinc Layer Thickness 5–12 μm (per ISO 4042)
Salt Spray Resistance ≥ 72 hours (white rust) per ISO 9227
RoHS / REACH Compliant — no hexavalent chromium (CR6)
Temperature Resistance Up to approx. 120°C continuous
Thread Tolerance Impact Minimal — standard nuts fit without modification
Hydrogen Embrittlement Risk Low risk for Grade 8.8 (below 1000 MPa threshold); baking recommended for Grade 10.9+
Corrosion Protection Suitable for indoor and sheltered outdoor environments

CR3 vs. CR6 — Why Trivalent Chromate Matters

Property CR6 (Hexavalent — Legacy) CR3 (Trivalent — This Product) ✅
RoHS Compliance ❌ Non-compliant ✅ Fully compliant
REACH Compliance ❌ Restricted (SVHC) ✅ Compliant
Health & Safety ❌ Carcinogenic (Cr⁶⁺) ✅ Non-toxic, safe
EU Market Access ❌ Restricted ✅ Unrestricted
Appearance Yellow / iridescent Bright silver / light iridescent
Corrosion Resistance Slightly higher Comparable for most applications

Surface Treatment Comparison — Zinc CR3 vs. Other Finishes

Property Zinc CR3 (This Product) Black Oxide Hot Dip Galvanised (HDG)
Coating Thickness 5–12 μm 0.5–1.5 μm 45–100 μm
Salt Spray (white rust) ≥ 72 hours 2–4 hours (bare) ≥ 1,000+ hours
Appearance Bright silver ✅ Matte black Matte grey
RoHS Compliant ✅ Yes (CR3) ✅ Yes ✅ Yes
Thread Fit Standard nuts fit ✅ Standard nuts fit ✅ Requires HDG nuts
Outdoor Service Life 2–5 years < 1 year (bare) 20–50+ years
Typical Application Indoor / light outdoor ✅ Automotive, machinery Structural outdoor
Cost Low ✅ Low Higher

Mechanical Properties — Grade 8.8 (ISO 898-1)

Property Grade 8.8 Value
Property Class 8.8 (per ISO 898-1 / DIN EN ISO 898-1)
Tensile Strength (Rm) min. 800 MPa (116,000 psi)
Proof Load Stress (Sp) min. 600 MPa
Yield Strength (Rp0.2) min. 640 MPa (80% of Rm)
Elongation (A) min. 12%
Reduction of Area (Z) min. 52%
Hardness min. 22 HRC / 250 HV
Hardness max. 32 HRC / 320 HV
Heat Treatment Quenched & Tempered (Q&T) for d > M16

Material Properties — 10B21 & 35K Steel

Property 10B21 (Boron Steel) 35K (Medium Carbon Steel)
GB/T Standard GB/T 6478 (CHQ Boron Steel) GB/T 699 (Medium Carbon Steel)
Carbon Content (C) 0.18–0.23% 0.32–0.39%
Boron (B) 0.0005–0.003% (key alloying element) None
Manganese (Mn) 0.70–1.00% 0.50–0.80%
Hardenability Excellent (boron-enhanced) Good
Cold Heading Excellent Good
Typical Use Grade 8.8 bolts M6–M24 Grade 8.8 bolts, general structural

Standard Cross-Reference

Standard Region Description
DIN 933 Germany / Europe Hexagon head bolts — full thread (metric)
ISO 4017 International Hexagon head screws — full thread, product grades A and B
GB 5783 China Hexagon head bolts — full thread (equivalent to DIN 933)
ISO 898-1 International Mechanical properties of fasteners — Grade 8.8 definition
ISO 4042 International Fasteners — electroplated zinc coating specification
ISO 9227 International Salt spray (fog) corrosion test
ISO 261 / DIN 13 International Metric coarse thread specification

Dimensional Specifications — DIN 933 / ISO 4017 Full Thread Hex Bolts

All dimensions in millimeters (mm). Data per DIN 933 / ISO 4017 standard.

Thread (d) Pitch (mm) s — A/F (mm) e — A/C (mm) k — Head Height (mm) d_w min (mm) Length Range (mm)
M3 0.5 5.5 6.01 2.0 4.6 6 – 30
M4 0.7 7 7.66 2.8 5.9 8 – 40
M5 0.8 8 8.79 3.5 6.9 10 – 50
M6 1.0 10 11.05 4.0 8.9 10 – 80
M8 1.25 13 14.38 5.3 11.6 16 – 100
M10 1.5 17 18.90 6.4 14.6 20 – 120
M12 1.75 19 21.10 7.5 16.6 25 – 150
M14 2.0 22 24.49 8.8 19.6 30 – 150
M16 2.0 24 26.75 10.0 22.5 35 – 200
M20 2.5 30 33.53 12.5 27.7 45 – 200
M24 3.0 36 39.98 15.0 33.3 50 – 200

* Custom sizes and lengths available on request. Contact FULLERKREG for non-standard requirements.

Standard Length Series — Available Bolt Lengths by Size

Thread Standard Lengths Available (mm)
M3 6, 8, 10, 12, 16, 20, 25, 30
M4 8, 10, 12, 16, 20, 25, 30, 35, 40
M5 10, 12, 16, 20, 25, 30, 35, 40, 45, 50
M6 10, 12, 16, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 80
M8 16, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 80, 90, 100
M10 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 80, 90, 100, 110, 120
M12 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 80, 90, 100, 110, 120, 130, 140, 150
M16 35, 40, 45, 50, 55, 60, 65, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 180, 200
M20 45, 50, 55, 60, 65, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 180, 200
M24 50, 55, 60, 65, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 180, 200

Tightening Torque Reference — Grade 8.8 Zinc CR3 (Lubricated, μ = 0.12)

Thread Torque (N·m) — 75% Proof Load Clamp Force (kN)
M3 0.9 2.5
M4 2.2 4.8
M5 4.5 7.8
M6 8 10.5
M8 20 20.5
M10 40 33.0
M12 70 48.0
M14 110 65.5
M16 170 87.0
M20 335 136.0
M24 580 195.0

* Torque values are for reference only. Actual requirements depend on friction coefficient, lubrication, joint material, and application. Always consult a qualified engineer for safety-critical applications.

Application Scenarios

  • 🔧 General industrial assembly — the most widely used structural bolt for machine frames, equipment enclosures, and general OEM assembly
  • 🏗️ Light structural construction — steel frame connections, mezzanine floors, racking systems, and shelving structures in indoor environments
  • 🚗 Automotive & transportation — body assembly, bracket fastening, and non-critical structural connections
  • 🏭 Manufacturing & production lines — conveyor systems, production equipment, and factory floor assembly
  • ⚡ Electrical & control panels — enclosure assembly, cable tray fastening, and switchgear installation
  • 📦 Logistics & warehousing — pallet racking, shelving systems, and storage equipment assembly
  • 🌊 Light outdoor & sheltered applications — covered structures, canopies, and sheltered industrial installations
  • 🤖 Robotics & automation — robot frames, conveyor structures, and automated equipment assembly

Product Gallery

FULLERKREG DIN 933 Grade 8.8 Bright Zinc Plated CR3 Full Thread Hex Bolts — actual product photos:

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

Ordering & Packaging Information

  • Packaging: Bulk carton / polybag per size and length; custom labeling available for OEM and distributor orders
  • MOQ: Contact FULLERKREG sales for wholesale minimum order quantities
  • Lead Time: Standard stock sizes ship promptly; large-volume orders subject to production schedule
  • Certifications: Material test reports (MTR), ISO 898-1 Grade 8.8 certificates, and ISO 4042 plating inspection reports available on request
  • Custom Requirements: Non-standard sizes, lengths, thread forms, and alternative surface treatments available — contact us

Frequently Asked Questions

Q: What is Zinc CR3 plating?
A: Zinc CR3 refers to electrolytic zinc plating followed by trivalent chromate (CR3) passivation. The zinc layer (5–12 μm) provides cathodic corrosion protection, while the CR3 passivation layer enhances corrosion resistance and gives the bright silver appearance. CR3 (trivalent chromium, Cr³⁺) replaces the older CR6 (hexavalent chromium) process, which is restricted under RoHS and REACH regulations.

Q: What is the difference between Zinc CR3 and Zinc CR6?
A: CR3 uses trivalent chromium (Cr³⁺), which is non-toxic and RoHS/REACH compliant. CR6 uses hexavalent chromium (Cr⁶⁺), which is classified as a carcinogen and is restricted under EU RoHS Directive and REACH regulation. FULLERKREG exclusively uses CR3 passivation to ensure full regulatory compliance for EU and global markets.

Q: Is Zinc CR3 suitable for outdoor use?
A: Zinc CR3 plating provides good corrosion protection for indoor and sheltered outdoor environments. For prolonged outdoor exposure, coastal environments, or aggressive industrial atmospheres, FULLERKREG recommends hot dip galvanised (HDG) Grade 8.8 bolts for significantly longer service life (20–50+ years vs. 2–5 years for zinc plating).

Q: Can standard nuts be used with Zinc CR3 bolts?
A: Yes. The thin zinc coating (5–12 μm) has minimal impact on thread dimensions, and standard DIN 934 / ISO 4032 Grade 8 hex nuts fit without modification. This is a key advantage over hot dip galvanised bolts, which require specially oversized HDG nuts.

Q: What does Grade 8.8 mean?
A: Grade 8.8 is a property class per ISO 898-1. The first number (8) indicates 1/100 of the nominal tensile strength: 8 × 100 = 800 MPa. The second number (8) indicates 80% of the tensile strength as the yield strength ratio: 800 × 0.8 = 640 MPa yield strength. Grade 8.8 is the standard structural bolt grade used worldwide.

Q: What is 10B21 steel?
A: 10B21 is a boron-alloyed cold heading quality (CHQ) steel per GB/T 6478. The boron addition (0.0005–0.003%) dramatically improves hardenability, allowing the steel to through-harden to Grade 8.8 mechanical properties even in larger diameters. It is the most widely used material for cost-effective Grade 8.8 bolt production globally.

Q: Can I get material test reports (MTR)?
A: Yes. FULLERKREG provides material test reports and ISO 898-1 Grade 8.8 compliance certificates upon request for wholesale and OEM orders.

FULLERKREG — Precision Fasteners to ISO/DIN/GB Standards. All technical data is provided for reference. Always verify fastener selection and torque requirements with a qualified engineer for structural and safety-critical applications.

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