Home » Full Thread Hex Bolts (ISO 4017) High Tensile Steel (A4-70)

Full Thread Hex Bolts (ISO 4017) High Tensile Steel (A4-70)

Full Thread Hex Bolts (ISO 4017 / DIN 933) — High Tensile Marine Stainless Steel A4-70 (SUS316)

FULLERKREG ISO 4017 / DIN 933 full thread hex bolts in A4-70 marine stainless steel (SUS316) combine high tensile strength with the superior corrosion resistance of molybdenum-enhanced austenitic stainless steel. Finished with whitened passivation for maximum surface protection, these bolts are the definitive choice for structural fastening in marine, offshore, chemical, and coastal environments where standard A2 stainless steel would suffer pitting or crevice corrosion. The fully threaded shank ensures maximum thread engagement and grip-length flexibility across all applications. Compliant with ISO 4017, DIN 933, and GB 5783 standards.

Product Highlights

  • Brand: FULLERKREG
  • Standards: ISO 4017 / DIN 933 / GB 5783
  • Material: A4 Marine Stainless Steel (SUS316 / X 2 Cr Ni Mo 17-12-2)
  • Property Class / Strength Grade: A4-70
  • 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
  • Key Advantage: Molybdenum (Mo 2.0–2.5%) — superior chloride & seawater corrosion resistance vs. A2

Why Choose FULLERKREG ISO 4017 A4-70 Full Thread Hex Bolts?

  • ✅ A4 (SUS316) marine grade — molybdenum-enhanced alloy for superior chloride, seawater, and pitting corrosion resistance vs. A2
  • ✅ A4-70 high tensile strength — Rm ≥ 700 MPa; combines marine corrosion resistance with structural-grade strength
  • ✅ 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 — ISO 4017 / DIN 933 / GB 5783 for global market acceptance
  • ✅ Non-magnetic (austenitic) — suitable for sensitive electronic and MRI-adjacent environments
  • ✅ Wholesale & bulk supply — available in large quantities for shipyards, distributors, and OEMs

A4-70 vs. A2-70 — Why Marine Grade Matters

Property A2-70 (SUS304) A4-70 (SUS316) — This Product
Tensile Strength (Rm) ≥ 700 MPa ≥ 700 MPa ✅ (Equal)
Proof Stress (Rp0.2) ≥ 450 MPa ≥ 450 MPa ✅ (Equal)
Molybdenum Content None 2.0–2.5% ✅
Seawater Resistance Moderate Excellent ✅
Pitting Corrosion Resistance Good Superior ✅
Crevice Corrosion Resistance Moderate Superior ✅
Chloride Resistance Limited Excellent ✅
Recommended for Marine Use Limited Yes ✅
Food & Pharma Grade Yes Yes ✅

Full Thread (ISO 4017) vs. Partial Thread (ISO 4014) — Key Differences

Feature ISO 4014 (Partial Thread) ISO 4017 (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 ISO 4014 / DIN 931 ISO 4017 / DIN 933 / GB 5783

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

All dimensions in millimeters (mm). Data strictly referenced from ISO 4017 / DIN 933 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 ISO 4017 / DIN 933. 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 — A4-70 Marine Stainless Steel (ISO 3506-1)

Property A4-70 Value
Property Class A4-70 (per ISO 3506-1)
Tensile Strength (Rm) min. 700 MPa
0.2% Proof Stress (Rp0.2) min. 450 MPa
Elongation (A) min. 20%
Reduction of Area (Z) min. 50%
Hardness min. 220 HV
Hardness max. 250 HV
Charpy Impact (KV) min. 50 J (at room temperature)

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 Non-magnetic (austenitic)
Operating Temperature −50°C to +300°C (continuous)
Key Advantage vs. A2 Molybdenum (Mo 2.0–2.5%) — enhanced pitting & crevice corrosion resistance

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.

Standard Cross-Reference

Standard Region Description
ISO 4017 International Hexagon head screws — full thread, product grades A and B
DIN 933 Germany / Europe Hexagon head bolts — full thread (equivalent to ISO 4017)
GB 5783 China Hexagon head bolts — full thread (equivalent to ISO 4017)
ISO 3506-1 International Mechanical properties of stainless steel fasteners — A4-70 grade definition
ISO 261 / DIN 13 International Metric coarse thread specification

Tightening Torque Reference — A4-70 Marine Stainless Steel

Recommended tightening torques for A4-70 stainless steel hex bolts (metric coarse thread, lubricated, μ = 0.12):

Thread Torque (N·m) — 75% Proof Load Clamp Force (kN)
M3 0.5 1.5
M4 1.2 2.8
M5 2.5 4.5
M6 4.5 6.5
M8 11 12.0
M10 22 19.5
M12 38 28.5
M14 61 39.0
M16 95 51.5
M20 185 80.0
M24 320 115.0

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

Application Scenarios

  • ⚓ Marine & offshore — deck hardware, hull structural connections, offshore platform fittings in seawater environments
  • 🏗️ Shipbuilding & shipyards — structural bolting in salt-air and seawater splash zones
  • 🌊 Coastal & port infrastructure — jetties, pontoons, harbour structures exposed to seawater spray and chlorides
  • 🏭 Chemical & petrochemical plants — high-load structural connections in chloride-rich, acidic, or caustic process environments
  • 🏭 Food, beverage & pharmaceutical — hygienic structural assembly requiring non-magnetic, high-purity stainless fasteners
  • 🌡️ Desalination & water treatment — high-chloride process environments where A2 would suffer pitting failure
  • 🏗️ Architectural & façade engineering — stainless structural connections in coastal buildings and curtain wall systems
  • ⚡ Renewable energy — offshore wind turbine structural fastening, tidal and wave energy installations

Product Gallery

FULLERKREG ISO 4017 / DIN 933 Full Thread Hex Bolts A4-70 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 A4-70 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 A4-70 better than A2-70 for marine applications?
A: A4 stainless steel (SUS316) contains 2.0–2.5% Molybdenum, which dramatically improves resistance to pitting and crevice corrosion caused by chloride ions in seawater and salt-laden atmospheres. A2 (SUS304) lacks this element and can suffer pitting failure in prolonged marine exposure. Both grades share the same A4-70 / A2-70 tensile strength of 700 MPa, so A4-70 delivers equal strength with far superior corrosion resistance.

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

Q: What does A4-70 mean?
A: A4 refers to the marine stainless steel grade (SUS316 / X 2 Cr Ni Mo 17-12-2), and 70 refers to the minimum tensile strength of 700 MPa per ISO 3506-1. A4-70 is the standard high tensile grade for marine stainless steel fasteners.

Q: Are A4-70 bolts suitable for permanent seawater immersion?
A: A4-70 (SUS316) provides excellent resistance to seawater and chloride environments. For permanent subsea immersion or highly aggressive offshore environments, consult a qualified corrosion engineer to confirm suitability and specify any additional protective measures.

Q: Are these bolts non-magnetic?
A: Yes. A4 (SUS316) is an austenitic stainless steel and is non-magnetic in the annealed condition, making it suitable for use near sensitive electronic equipment or in MRI-adjacent environments.

Q: What nuts and washers are compatible?
A: Use ISO 4032 / DIN 934 hex nuts (A4-70) 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 A4-70 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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