DIN 934 High Strength Hex Nut - Alloy Steel 10B21, Black Oxide, Class 10
FULLERKREG DIN 934 Class 10 High Strength Hexagon Nuts in alloy steel 10B21 with black oxide surface treatment deliver exceptional clamping force and a distinctive matte black appearance. Manufactured to DIN 934 / ISO 4032 at strength Class 10, these nuts are engineered for heavy structural, automotive, and high-load industrial applications where maximum proof load and a professional black finish are both required. The black oxide treatment provides mild corrosion resistance and eliminates light reflection, ideal for exposed assemblies and precision machinery.
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Material: Alloy Steel 10B21 (quenched and tempered)
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Surface Treatment: Black Oxide (hot alkaline blackening)
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Strength Class: Class 10 (ISO 898-2)
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Standard: DIN 934 / ISO 4032
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Thread: Metric Coarse (ISO 68-1)
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Size Range: M5 to M36
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Drive Type: Hexagon (6-sided)
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Mating Bolt Class: 10.9
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Appearance: Uniform matte black finish; no dimensional change from coating
Dimensional Data - DIN 934 High Strength Hex Nut Black Class 10
All dimensions in mm. Tolerances per DIN 934 / ISO 4032. Unit weight based on alloy steel density 7.85 g/cm3, excluding coating.
| Thread |
Pitch (mm) |
s (mm) |
e (mm) |
m (mm) |
Weight (g/pc) |
| M5 |
0.80 |
8.00 |
9.24 |
4.00 |
1.58 |
| M6 |
1.00 |
10.00 |
11.55 |
5.00 |
3.06 |
| M8 |
1.25 |
13.00 |
15.01 |
6.50 |
6.72 |
| M10 |
1.50 |
17.00 |
19.64 |
8.00 |
13.30 |
| M12 |
1.75 |
19.00 |
21.94 |
10.00 |
21.70 |
| M14 |
2.00 |
22.00 |
25.40 |
11.00 |
34.60 |
| M16 |
2.00 |
24.00 |
27.71 |
13.00 |
51.40 |
| M18 |
2.50 |
27.00 |
31.18 |
15.00 |
79.10 |
| M20 |
2.50 |
30.00 |
34.64 |
16.00 |
106.80 |
| M22 |
2.50 |
32.00 |
36.95 |
18.00 |
146.20 |
| M24 |
3.00 |
36.00 |
41.57 |
19.00 |
193.80 |
| M27 |
3.00 |
41.00 |
47.34 |
22.00 |
291.50 |
| M30 |
3.50 |
46.00 |
53.12 |
24.00 |
414.80 |
| M33 |
3.50 |
50.00 |
57.74 |
26.00 |
553.60 |
| M36 |
4.00 |
55.00 |
63.51 |
29.00 |
751.20 |
s = Width Across Flats | e = Width Across Corners | m = Nut Height
Alloy Steel 10B21 - Material Overview
10B21 is a boron-treated alloy steel specifically engineered for high-strength fastener applications. The addition of boron (0.0005-0.003%) significantly enhances hardenability, allowing Class 10 proof load performance to be achieved with a leaner alloy composition compared to conventional alloy steels.
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Boron Addition: 0.0005-0.003% B - dramatically improves through-hardening capability
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High Hardenability: Uniform hardness distribution across full cross-section after Q&T
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Superior Fatigue Resistance: Optimized for cyclic loading in structural and automotive joints
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Weldability: Lower carbon equivalent vs. standard alloy steels; better weldability
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Cost Efficiency: Achieves Class 10 performance with minimal alloy additions
Black Oxide Surface Treatment
FULLERKREG applies hot alkaline black oxide treatment to all Class 10 DIN 934 hex nuts, creating a uniform magnetite (Fe3O4) layer on the steel surface.
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Coating Thickness: Less than 1 micron - zero dimensional change; thread tolerance fully maintained
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Appearance: Uniform matte black finish; no flaking or peeling
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Anti-Glare: Eliminates light reflection - ideal for optical and precision instrument assemblies
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Corrosion Resistance: Mild protection; enhanced with post-treatment oil or wax coating
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No Hydrogen Embrittlement Risk: Chemical conversion process - no electrolytic plating involved
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RoHS Compliant: No heavy metals; environmentally safe process
Black Oxide vs. Zinc Plating
| Property |
Black Oxide |
Zinc Plated Cr3 |
| Appearance |
Matte black |
Bright silver-blue |
| Coating Thickness |
Less than 1 micron |
5-12 microns |
| Salt Spray bare |
2-4 hours |
72+ hours |
| Salt Spray oiled |
24-48 hours |
120+ hours |
| Thread Fit Impact |
None |
Minor |
| Light Reflection |
None (anti-glare) |
High |
| Best For |
Tooling, optics, aesthetics |
Outdoor / corrosive environments |
Selection Guide - DIN 934 vs. Related Standards
| Standard |
Profile |
Height |
Typical Use |
| DIN 934 / ISO 4032 |
Standard hex |
Normal ~0.8d |
General fastening - most common |
| DIN 439 / ISO 4035 |
Thin hex |
Low ~0.5d |
Jam nut / lock nut |
| DIN 985 / ISO 10511 |
Nylon insert lock nut |
Higher |
Vibration / reusable locking |
| DIN 936 |
Thin nut |
Very low ~0.4d |
Fine-pitch adjustment |
Strength Class Comparison
| Property |
Class 6 |
Class 8 |
Class 10 |
Class 12 |
| Proof Load Stress |
600 MPa |
800 MPa |
1040 MPa |
1150 MPa |
| Material |
Med. carbon |
Med. carbon Q&T |
Alloy steel Q&T |
Alloy steel Q&T |
| Mating Bolt |
5.8 / 6.8 |
8.8 |
10.9 |
12.9 |
| Hardness |
150-302 HV |
200-302 HV |
272-353 HV |
295-380 HV |
Standard Specification
- Thread tolerance: 6H per ISO 965-1
- Mechanical properties: Class 10 per ISO 898-2 (proof load stress 1040 MPa)
- Hardness: 272-353 HV
- Dimensional tolerance: Grade A for M5-M16; Grade B for M18-M36
- Surface treatment: Hot alkaline black oxide; coating thickness less than 1 micron
- Post-treatment: Oil or wax coating to enhance corrosion resistance
Mechanical Properties - Class 10
| Property |
Value |
Standard |
| Proof Load Stress |
1040 MPa |
ISO 898-2 |
| Hardness |
272-353 HV |
ISO 898-2 |
| Mating Bolt Class |
10.9 |
ISO 898-2 |
| Material Condition |
Quenched and Tempered |
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| Density |
7.85 g/cm3 |
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| Operating Temperature |
-50 to +300 deg C |
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Chemical Composition - Alloy Steel 10B21
| Element |
C |
Mn |
P |
S |
B (Boron) |
| 10B21 |
0.18-0.23% |
0.80-1.10% |
max 0.030% |
max 0.030% |
0.0005-0.003% |
Typical Applications
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Heavy Structural Steel Construction - High-load bolted connections requiring Class 10.9 bolt assemblies
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Automotive and Motorsport - Engine mounts, suspension systems, roll cages demanding maximum clamping force
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Mining and Heavy Equipment - Vibration-intensive environments where high proof load is critical
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Wind Energy and Power Generation - Tower flange connections and turbine assembly joints
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Precision Machinery - CNC machine tool assemblies where black finish and high strength are both specified
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Architectural Metalwork - Exposed high-load connections requiring a premium black aesthetic
Product Gallery - DIN 934 High Strength Hex Nut Black Class 10
Why Choose FULLERKREG?
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Direct Manufacturer - No middlemen; factory-direct pricing on all standard and custom sizes
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Strict Dimensional Control - 100% thread gauge inspection; CMM verification on critical dimensions
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Material Traceability - Full mill certificates and surface treatment reports available per batch
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Flexible MOQ and Packaging - Bulk bags, small boxes, or custom packaging; MOQ from 100 pcs
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Global Shipping - Export experience to 50+ countries; DDP/FOB/CIF terms available
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Fast Lead Times - Standard sizes in stock; custom sizes within 15-25 business days
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Full Documentation - CoC, MTC, RoHS, REACH compliance documents on request
