Home » Full Thread Hex Bolts (DIN 933) - High Tensile Stainless Steel (A4-80)

Full Thread Hex Bolts (DIN 933) - High Tensile Stainless Steel (A4-80)

Full Thread Hex Bolts (DIN 933 / GB 5783) — Ultra-High Tensile Marine Stainless Steel A4-80 (SUS316)

FULLERKREG DIN 933 / GB 5783 full thread hex bolts in A4-80 grade represent the pinnacle of stainless steel fastener performance — combining the highest strength class available in ISO 3506-1 (800 MPa minimum tensile strength) with the superior chloride and seawater corrosion resistance of A4 marine stainless steel (SUS316). Achieved through cold working of molybdenum-enhanced austenitic stainless steel and finished with whitened passivation, these bolts are engineered for the most demanding structural applications in aggressive marine, chemical, and offshore environments. The fully threaded shank ensures maximum thread engagement and grip-length flexibility.

Product Highlights

  • Brand: FULLERKREG
  • Standards: DIN 933 / GB 5783 / ISO 4017
  • Material: A4 Marine Stainless Steel (SUS316 / X 2 Cr Ni Mo 17-12-2)
  • Property Class / Strength Grade: A4-80 (Highest Grade — ISO 3506-1)
  • Thread Type: Full Thread (Fully Threaded Shank)
  • Surface Treatment: Whitened & Passivated (酸洗钝化)
  • Head Type: Hexagon (Hex Head)
  • Size Range: M3 – M24
  • Thread: Metric coarse thread per ISO 261 / DIN 13
  • Dual Advantage: Highest stainless strength (800 MPa) + Best marine corrosion resistance (Mo 2.0–2.5%)

Why Choose FULLERKREG DIN 933 A4-80 Full Thread Hex Bolts?

  • ✅ A4-80 — the ultimate stainless fastener grade — Rm ≥ 800 MPa, the highest strength class in ISO 3506-1 for stainless steel
  • ✅ A4 (SUS316) marine grade — molybdenum-enhanced alloy for superior chloride, seawater, and pitting corrosion resistance
  • ✅ Best of both worlds — maximum strength AND maximum marine corrosion resistance in a single fastener
  • ✅ Full thread design — maximum thread engagement; ideal for through-bolting and variable grip-length applications
  • ✅ Passivated finish — enhanced chromium-molybdenum oxide passive layer for maximum long-term corrosion protection
  • ✅ Triple standard compliance — DIN 933 / GB 5783 / ISO 4017 for global market acceptance
  • ✅ Wholesale & bulk supply — available in large quantities for shipyards, offshore contractors, and OEMs

Complete Grade Comparison — A4-80 vs. All Stainless Grades

Property A2-50 A2-70 A4-70 A2-80 A4-80 — This Product
Tensile Strength (Rm) min. 500 MPa 700 MPa 700 MPa 800 MPa 800 MPa ✅
Proof Stress (Rp0.2) min. 210 MPa 450 MPa 450 MPa 600 MPa 600 MPa ✅
Elongation (A) min. 40% 20% 20% 8% 8%
Molybdenum (Mo) None None 2.0–2.5% None 2.0–2.5% ✅
Marine / Chloride Resistance Moderate Moderate Excellent Moderate Excellent ✅
Strength Level Standard High High Ultra-High Ultra-High ✅
Best For General use Structural Marine structural High-load indoor Heavy marine structural ✅

Full Thread (DIN 933) vs. Partial Thread (DIN 931) — Key Differences

Feature DIN 931 (Partial Thread) DIN 933 (Full Thread) — This Product
Thread Coverage Partial — unthreaded shank section Full — entire shank threaded ✅
Grip Length Flexibility Fixed by unthreaded shank Adjustable — any grip length ✅
Thread Engagement Limited to threaded portion Maximum — full shank ✅
Typical Use Precision clearance-hole bolting Through-bolting, clamping, variable thickness ✅
Equivalent Standards DIN 931 / ISO 4014 DIN 933 / ISO 4017 / GB 5783

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

All dimensions in millimeters (mm). Data strictly referenced from DIN 933 / ISO 4017 standard drawings.

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
M18 2.5 27 30.14 11.5 24.9 40 – 200
M20 2.5 30 33.53 12.5 27.7 45 – 200
M22 2.5 34 37.72 14.0 31.4 50 – 200
M24 3.0 36 39.98 15.0 33.3 50 – 200

* s = Width across flats (A/F); e = Width across corners (A/C); k = Head height; d_w = Bearing surface diameter. All dimensions per DIN 933 / ISO 4017. For full tolerance tables, refer to the complete standard.

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
M14 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

* Non-standard lengths available on request. Contact FULLERKREG for custom length requirements.

Mechanical Properties — A4-80 Marine Stainless Steel (ISO 3506-1)

Property A4-80 Value
Property Class A4-80 (per ISO 3506-1) — Highest Stainless Grade
Tensile Strength (Rm) min. 800 MPa
0.2% Proof Stress (Rp0.2) min. 600 MPa
Elongation (A) min. 8%
Reduction of Area (Z) min. 25%
Hardness min. 250 HV
Hardness max. 320 HV
Achievable by Cold working / strain hardening of A4 (SUS316) austenitic stainless steel

⚠️ Note: A4-80 strength is achieved through cold working (strain hardening) of A4 stainless steel. This significantly increases tensile and proof strength while reducing elongation compared to A4-70. The material remains fully austenitic and retains its superior marine corrosion resistance. Cold-worked A4-80 may exhibit slight magnetic response — this does not affect corrosion resistance.

Material Properties — A4 Marine Stainless Steel (SUS316)

Property Value
Material Designation A4 / SUS316 / X 2 Cr Ni Mo 17-12-2
UNS No. S31600
Corrosion Resistance Excellent — superior to A2 in chloride & marine environments
Magnetic Slightly magnetic after cold working (austenitic base)
Operating Temperature −50°C to +300°C (continuous)
Key Advantage vs. A2-80 Molybdenum (Mo 2.0–2.5%) — superior pitting & crevice corrosion resistance in chloride environments

Chemical Composition — A4 (SUS316) Marine Stainless Steel

Element C (%) Si (%) Mn (%) P (%) S (%) Cr (%) Ni (%) Mo (%)
A4 / X 2 Cr Ni Mo 17-12-2 ≤ 0.03 ≤ 1.0 ≤ 2.0 ≤ 0.045 ≤ 0.03 16.5–18.5 10.0–13.0 2.0–2.5

The addition of Molybdenum (Mo 2.0–2.5%) is the defining characteristic of A4/316 stainless steel, providing significantly enhanced resistance to pitting corrosion in chloride-rich environments such as seawater, de-icing salts, and industrial chemicals — retained even after cold working to A4-80 strength.

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 3506-1 International Mechanical properties of stainless steel fasteners — A4-80 grade definition
ISO 261 / DIN 13 International Metric coarse thread specification

Tightening Torque Reference — A4-80 Marine Stainless Steel

Recommended tightening torques for A4-80 stainless steel hex bolts (metric coarse thread, lubricated, μ = 0.12). Higher proof stress vs. A4-70 allows greater preload at the same torque:

Thread Torque (N·m) — 75% Proof Load Clamp Force (kN)
M3 0.6 1.8
M4 1.5 3.4
M5 3.0 5.5
M6 5.5 8.0
M8 13 14.5
M10 27 23.5
M12 47 34.5
M14 75 47.0
M16 115 62.0
M20 225 97.0
M24 390 139.0

* 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

  • ⚓ Offshore & subsea structures — platform structural connections, subsea equipment fastening requiring maximum strength and seawater resistance
  • 🏗️ Shipbuilding & heavy marine engineering — high-load structural bolting in hull, deck, and superstructure in salt-air and seawater environments
  • ⚡ Offshore wind & tidal energy — monopile and jacket structure fastening where both extreme loads and seawater exposure are present
  • 🏭 Chemical & petrochemical plants — high-pressure flange connections in chloride-rich, acidic, or caustic marine process environments
  • 🌊 Coastal & port infrastructure — high-load structural connections in jetties, breakwaters, and harbour structures
  • 🚂 Rail & transportation in coastal regions — structural fastening requiring both maximum strength and marine corrosion resistance
  • 🏭 Desalination & water treatment plants — high-load connections in high-chloride process environments
  • 🔧 Heavy OEM & machinery in marine environments — maximum preload fastening where both strength and corrosion resistance are non-negotiable

Product Gallery

FULLERKREG DIN 933 Full Thread Hex Bolts A4-80 Marine Stainless Steel — 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, shipyard, 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 3506-1 A4-80 compliance certificates, and third-party inspection reports available on request
  • Custom Requirements: Non-standard lengths, special thread forms, and custom markings available — contact us

Frequently Asked Questions

Q: What makes A4-80 the ultimate stainless fastener grade?
A: A4-80 combines two key advantages: the highest strength class in ISO 3506-1 (Rm ≥ 800 MPa, Rp0.2 ≥ 600 MPa) with the superior marine corrosion resistance of A4 (SUS316) stainless steel containing 2.0–2.5% Molybdenum. No other standard stainless fastener grade offers both maximum strength and maximum marine corrosion resistance simultaneously.

Q: How is A4-80 strength achieved?
A: A4-80 strength is achieved through cold working (strain hardening) of A4 (SUS316) austenitic stainless steel. This process increases tensile and proof strength significantly without changing the chemical composition or corrosion resistance of the material.

Q: What is the difference between A4-80 and A4-70?
A: Both grades use A4 (SUS316) marine stainless steel. A4-80 has higher tensile strength (800 MPa vs. 700 MPa) and proof stress (600 MPa vs. 450 MPa), achieved through cold working. A4-70 has higher elongation (20% vs. 8%) and is fully non-magnetic. A4-80 is preferred for maximum preload and high-fatigue applications.

Q: Will A4-80 bolts be slightly magnetic?
A: Cold-worked A4-80 stainless steel may exhibit a slight magnetic response due to strain-induced martensite transformation. This does not affect corrosion resistance. For strictly non-magnetic applications, specify A4-70 grade bolts instead.

Q: What is the difference between DIN 933 and DIN 931?
A: DIN 933 (ISO 4017 / GB 5783) specifies fully threaded hex bolts. DIN 931 (ISO 4014) specifies partially threaded hex bolts with an unthreaded shank section. Full thread bolts offer greater grip-length flexibility and maximum thread engagement.

Q: What nuts and washers are compatible?
A: Use ISO 4032 / DIN 934 hex nuts (A4-70 or A4-80) and ISO 7089 / DIN 125 flat washers (A4) for a fully matched marine stainless steel assembly. FULLERKREG supplies the complete range of compatible A4 stainless fasteners.

Q: Can I get material test reports (MTR)?
A: Yes. FULLERKREG provides material test reports and ISO 3506-1 A4-80 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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