DIN 914 / ISO 4027 — Socket Set Screw with Cone Point | A4 Stainless Steel (Marine Grade)
Brand: FULLERKREG | Material: A4 Stainless Steel (SUS316 / 1.4401) | Surface: Passivated (Bright Finish)
Product Overview
FULLERKREG DIN 914 / ISO 4027 Socket Set Screws with Cone Point in A4 Stainless Steel (SUS316) combine the maximum mechanical locking performance of the cone point geometry with the superior corrosion resistance of marine-grade stainless steel. The addition of 2.0–2.5% molybdenum to the SUS316 alloy delivers significantly enhanced resistance to chloride-induced pitting and crevice corrosion compared to standard A2 (SUS304), making these set screws the definitive choice for permanent shaft locking in marine, offshore, chemical processing, desalination, and high-salinity industrial environments.
The cone point — a sharp, conical tip — seats into a matching conical recess on the shaft, creating a self-centering, positive mechanical lock with exceptional resistance to rotation and axial displacement under vibration and dynamic loads. Combined with a bright passivated finish, these set screws deliver long-term reliability in the most demanding corrosive environments.
Standards & Specifications
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Standards: DIN 914 (1987), ISO 4027
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Thread Form: ISO Metric Coarse Thread (per ISO 68-1)
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Thread Tolerance: 6g (per ISO 965-1)
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Drive Type: Hexagon Socket (Allen / Hex Key)
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Point Type: Cone Point — included angle 90° (M1.6–M8) / 120° (M10 and above), per DIN 914
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Material: A4 Stainless Steel (SUS316 / 1.4401)
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Material Grade: A4 per ISO 3506-3
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Surface Treatment: Passivated — bright, clean finish
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Mechanical Properties Standard: ISO 3506-3
Material & Mechanical Properties
| Property |
Value |
Standard |
| Material |
A4 Stainless Steel (SUS316 / 1.4401) |
ISO 3506-3 |
| Cr Content |
16.5 – 18.5% |
— |
| Ni Content |
10.0 – 13.0% |
— |
| Mo Content |
2.0 – 2.5% |
— |
| Min. Tensile Strength |
700 MPa (A4-70) |
ISO 3506-3 |
| Hardness (typical) |
HV 200 – 300 |
ISO 3506-3 |
| Thread Tolerance |
6g |
ISO 965-1 |
| Surface |
Passivated (Bright / 洗白钝化) |
— |
| Magnetic |
Slightly (work-hardened) |
— |
| Operating Temp. |
-196°C to +800°C (intermittent) |
— |
Why A4 (SUS316)? — The Role of Molybdenum
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Pitting resistance: Mo dramatically increases resistance to chloride-induced pitting — the primary failure mode of A2 in marine environments.
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Crevice corrosion resistance: Superior in tight joints and threaded connections where oxygen depletion creates aggressive local chemistry.
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Higher PREN: SUS316 PREN ~24–26 vs. SUS304 ~18–20 — significant improvement in chloride tolerance.
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Acid resistance: Better resistance to dilute H₂SO₄, H₃PO₄, and organic acids vs. A2.
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Long-term reliability: A4 maintains integrity significantly longer than A2 in marine/chemical environments, reducing maintenance costs.
Cone Point Geometry — Design & Function
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Included angle: 90° for M1.6–M8; 120° for M10 and above (per DIN 914).
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Permanent locking: Seats into a matching conical shaft recess — positive, self-centering lock resisting rotation and axial displacement.
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Maximum holding force: Highest axial and torsional holding force among all set screw point types when used with a matching recess.
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Self-centering: Conical geometry ensures precise, repeatable positioning.
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Vibration resistance: Excellent under dynamic, cyclic, and shock loads.
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Permanent installation: Creates a permanent indent in the shaft — plan position carefully before final tightening.
Point Type Comparison — Selection Guide
| Point Type |
Holding Force |
Shaft Damage |
Repositionable |
Best For |
| Cone Point (DIN 914) |
Maximum |
High (permanent) |
No |
Permanent locking, precision positioning |
| Cup Point (DIN 916) |
High |
Moderate |
Limited |
General shaft locking, vibration resistance |
| Flat Point (DIN 913) |
Moderate |
Minimal |
Yes |
Soft shafts, frequent adjustment |
| Oval Point (DIN 915) |
Moderate |
Minimal |
Yes |
Delicate surfaces, adjustment screws |
Surface Treatment: Passivation (洗白钝化)
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Process: Acid passivation removes free iron, machining residues, and surface contaminants.
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Result: Bright, silver-white finish with reinforced Cr-Mo oxide passive layer.
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Benefit: Maximizes SUS316 corrosion resistance — critical in chloride environments where surface contamination initiates pitting.
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Appearance: Uniform bright metallic finish — no discoloration, no scale, no heat tint.
Dimensional Range
| Thread |
Pitch (mm) |
Socket s (mm) |
Cone Angle |
Length Range (mm) |
| M3 |
0.5 |
1.5 |
90° |
3 – 16 |
| M4 |
0.7 |
2.0 |
90° |
4 – 20 |
| M5 |
0.8 |
2.5 |
90° |
5 – 25 |
| M6 |
1.0 |
3.0 |
90° |
6 – 30 |
| M8 |
1.25 |
4.0 |
90° |
8 – 40 |
| M10 |
1.5 |
5.0 |
120° |
10 – 50 |
| M12 |
1.75 |
6.0 |
120° |
12 – 60 |
| M16 |
2.0 |
8.0 |
120° |
16 – 80 |
| M20 |
2.5 |
10.0 |
120° |
20 – 100 |
| M24 |
3.0 |
12.0 |
120° |
25 – 120 |
Custom lengths and configurations available. Contact FULLERKREG for non-standard requirements.
Corrosion Resistance
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Excellent: Seawater, marine atmosphere, coastal environments, chloride solutions, brine, de-icing salts.
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Excellent: Dilute H₂SO₄, H₃PO₄, acetic acid, and many organic acids.
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Good: Food acids, alkalis, most industrial chemicals.
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Superior to A2 in all chloride-containing environments due to Mo content.
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Not recommended for concentrated oxidizing acids or high-temperature halide environments without engineering review.
Typical Applications
- Marine and offshore — deck hardware, rigging, winches, underwater assemblies
- Coastal and harbor infrastructure exposed to salt spray
- Permanent shaft locking in corrosive environments
- Chemical processing — pumps, valves, agitators, reactors
- Desalination and water treatment equipment
- Food and beverage — washdown and CIP environments
- Pharmaceutical manufacturing — sterile and high-purity environments
- Swimming pool and aquatic facility equipment
- Oil & gas topside and subsea assemblies
- Precision positioning with conical shaft recesses in corrosive environments
A4 vs. A2 — Comparison
| Property |
A4 / SUS316 (This Product) |
A2 / SUS304 |
| Corrosion Resistance |
Superior (Mo-enhanced) |
Good |
| Chloride / Marine |
Excellent |
Moderate |
| Seawater Immersion |
Good |
Not recommended |
| PREN Value |
~24–26 |
~18–20 |
| Tensile Strength |
700 MPa (A4-70) |
700 MPa (A2-70) |
| Food / Pharma |
Yes |
Yes |
| Appearance |
Bright silver-white |
Bright silver-white |
| Cost |
Premium |
Standard |
Installation Guidelines
- Use the correct hex key size — refer to dimensional table above.
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Shaft preparation: Drill a matching conical recess (90° for M3–M8; 120° for M10+) for maximum holding force.
- Clean shaft and bore thoroughly before installation.
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Anti-galling (critical): Apply MoS₂ or nickel-based anti-seize to threads before tightening — stainless is prone to cold welding.
- Tighten slowly with a calibrated torque wrench — avoid power tools.
- If seizure begins, back off immediately, re-apply anti-seize, and retry.
- For vibration-critical use, add stainless-compatible thread-locking compound.
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Permanence note: Cone point creates a permanent shaft indent — plan position carefully before final tightening.
Quality Assurance
- 100% thread gauge inspection per ISO 965-1 (6g); cone angle verification per DIN 914
- PMI spectrometer analysis confirming SUS316 composition including Mo content
- Vickers hardness test per ISO 3506-3
- Tensile / proof load testing per ISO 3506-3 (A4-70)
- Salt spray test post-passivation
- Socket torque test
- Full lot traceability; mill certificates available on request
Packaging & Ordering
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Packaging: Bulk (polybag/carton), small box (per size), or custom OEM packaging
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Price: Unit price per piece (USD) — contact us for volume pricing
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Customers: B2B wholesale only — no retail / B2C
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Orders: Placed offline via email — online prices for reference only
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Lead Time: ~30 days DDP (small batch); FOB Shanghai for large volumes
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Mill Certificates: Available on request (SUS316 + Mo content)
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Custom: Non-standard lengths, configurations, OEM available on request
Frequently Asked Questions
Q: What is the difference between DIN 914 and ISO 4027?
A: DIN 914 is the German standard; ISO 4027 is the international equivalent. Both are dimensionally interchangeable. FULLERKREG products comply with both.
Q: What is the cone angle?
A: 90° for M1.6–M8; 120° for M10 and above (per DIN 914). Use the matching countersink angle when drilling the shaft recess.
Q: What does A4 stainless mean?
A: A4 = SUS316 / 1.4401 per ISO 3506-3 — 16–18% Cr, 10–13% Ni, 2–2.5% Mo. Molybdenum gives significantly superior chloride pitting resistance vs. A2 (SUS304).
Q: Why choose A4 over A2?
A: In marine or high-chloride environments, A2 is susceptible to pitting at the threaded joint and cone contact area — exactly where crevice conditions are worst. A4 resists this, ensuring long-term holding force and integrity.
Q: Do I need to drill a shaft recess?
A: For maximum holding force, yes — drill a matching conical recess. The cone point can engage a flat shaft, but holding force is reduced and shaft damage more pronounced.
Q: What is passivation (洗白钝化)?
A: An acid treatment removing free iron and contaminants, enhancing the Cr-Mo oxide passive layer for maximum corrosion resistance and a bright finish.
Q: Suitable for seawater immersion?
A: A4 (SUS316) handles seawater splash and marine atmosphere excellently, and intermittent immersion well. For continuous full immersion under high stress, super-duplex grades may be needed. Contact FULLERKREG for guidance.
Q: Why do stainless set screws seize during installation?
A: Stainless work-hardens under friction, causing galling (cold welding). Always use MoS₂ or nickel anti-seize and tighten slowly with a torque wrench.
Q: Can I get mill certificates?
A: Yes — FULLERKREG provides SUS316 mill certificates including Mo content on request.
Q: Custom lengths or pitches available?
A: Yes. Contact FULLERKREG with your technical requirements.
