Home » Weld Nuts (DIN 929) - 10B21 Medium-Strength Steel - ISO Class 10 Bare

Weld Nuts (DIN 929) - 10B21 Medium-Strength Steel - ISO Class 10 Bare

Weld Nuts (DIN 929) — 10B21 Medium-Strength Steel, ISO Class 10, Bare

FULLERKREG DIN 929 hexagon weld nuts in 10B21 boron-alloyed medium-strength carbon steel deliver high weld performance and superior mechanical strength for demanding automotive, structural, and heavy-equipment applications. Manufactured to the DIN 929 standard, each nut features three symmetrically arranged welding projections on the bearing face that collapse and fuse with the base material during resistance welding, creating a flush, permanent, high-strength joint. The bare (uncoated) surface finish is ideal for applications where post-weld painting, powder coating, or e-coating will be applied, or where the base metal appearance is acceptable. 10B21 boron steel achieves ISO Class 10 mechanical performance — significantly stronger than standard carbon steel grades — making it the preferred choice for high-load weld nut applications. Available in thread sizes M3 through M16.

Dimensional Data

All dimensions in mm. Tolerances per DIN 929. Unit weight (g) is theoretical reference value for carbon steel (density 7.85 g/cm³).

Thread
d		 Pitch
(mm)		 Nut Height
m (h14)		 Across Flats
s (h13)		 Across Corners
e (min)		 Spigot Dia.
d2 (tol d11)		 Spigot Proj.
h1 (tol)		 Weld Proj.
h2 (tol)		 Unit Weight
(g/pc)
M3 0.5 3.00 7.50 8.27 4.50 0.55 ±0.1 0.25 +0/-0.1 ~0.9
M4 0.7 3.50 9.00 9.91 6.00 0.65 ±0.1 0.35 +0/-0.1 ~1.6
M5 0.8 4.00 10.00 11.05 7.00 0.70 ±0.1 0.40 +0/-0.1 ~2.3
M6 1.0 5.00 11.00 12.12 8.00 0.75 ±0.15 0.50 +0/-0.1 ~3.7
M8 1.25 6.50 14.00 15.44 10.50 0.90 ±0.15 0.50 +0/-0.15 ~7.3
M10 1.5 8.00 17.00 18.72 12.50 1.15 ±0.2 0.65 +0/-0.15 ~13.8
M12 1.75 10.00 19.00 20.88 14.80 1.40 ±0.2 0.80 +0/-0.2 ~21.9
M14 2.0 10.00 19.00 20.88 14.80 1.40 ±0.2 1.00 +0/-0.2 ~24.1
M16 2.0 10.00 24.00 26.75 18.80 1.80 ±0.2 1.00 +0/-0.2 ~37.0

* Across Corners (e) calculated from s × 1.155. Unit weights are theoretical reference values; actual weights may vary ±5%. M14 has limited availability — higher MOQ applies.

Selection Guide

Parameter Specification
Standard DIN 929
Material 10B21 Boron-Alloyed Medium-Strength Carbon Steel
Surface Treatment Bare (Uncoated / Mill Finish)
ISO Property Class Class 10 (per ISO 898-2)
Thread Type Metric coarse thread (ISO 68-1)
Thread Tolerance 6H
Nut Height Tolerance h14
Across Flats Tolerance h13
Spigot Diameter Tolerance d11
Welding Projections 3 projections, symmetrically arranged
Welding Method Resistance spot welding
Thread Size Range M3 – M16
Proof Load Stress ≥ 900 MPa (Class 10)
Tensile Strength ≥ 1040 MPa (Class 10)
Hardness 272–353 HV (Class 10)
Corrosion Resistance Low (bare steel — post-process coating recommended for corrosive environments)
Typical Post-Process E-coat, powder coat, paint, zinc plating (by customer)
RoHS Compliant Yes
Packaging Bulk bag / box; custom packaging available

Standard Notes

DIN 929 specifies hexagon weld nuts with three welding projections on the bearing face. The spigot (pilot) locates the nut precisely on the workpiece prior to welding. Upon resistance welding, the projections collapse and fuse with the base material, creating a flush, permanent joint. 10B21 is a boron-alloyed low-carbon steel (SAE 10B21 / GB 10B21) widely used in the automotive industry for high-strength weld nuts and fasteners. The boron addition (0.0005–0.003%) significantly improves hardenability, enabling ISO Class 10 mechanical performance without the need for alloy-heavy compositions. The bare surface is the standard delivery condition for automotive body-in-white and structural applications where the assembly will receive a subsequent coating process.

  • DIN 929 — Hexagon weld nuts, metric coarse thread
  • Material: 10B21 boron-alloyed carbon steel (SAE 10B21 equivalent)
  • Property Class: ISO Class 10 per ISO 898-2
  • Surface: Bare / uncoated mill finish — no plating, no coating
  • Thread: Right-hand, metric coarse, tolerance class 6H
  • Key advantage: High strength-to-cost ratio; ideal for automotive BIW and structural weld assemblies

Material Grade Comparison — DIN 929 Weld Nuts

Grade Material ISO Class Tensile Strength Corrosion Resistance Typical Application
10B21 Bare ✓ Boron carbon steel Class 10 ≥ 1040 MPa Low (bare) Automotive BIW, structural, pre-coat assemblies
A2 (SUS304) Stainless steel A2-70 ≥ 700 MPa Good General industrial, indoor/outdoor
A4 (SUS316) Marine stainless A4-70 ≥ 700 MPa Excellent Marine, chemical, food-grade

Product Gallery

DIN 929 Hex Weld Nuts — 10B21 Carbon Steel, ISO Class 10, Bare actual product photos:

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

Chemical Composition — 10B21 Boron-Alloyed Carbon Steel

Grade C (%) Mn (%) P (%) S (%) Si (%) B (%)
10B21 0.18–0.23 0.80–1.10 ≤ 0.030 ≤ 0.030 0.15–0.35 0.0005–0.003

* The boron (B) micro-addition is the key feature of 10B21, significantly improving hardenability and enabling ISO Class 10 strength levels from a low-carbon base composition. Equivalent to SAE 10B21 / GB 10B21.

Mechanical Properties — ISO Class 10 (ISO 898-2)

Property Class Proof Load Stress (MPa) Tensile Strength (MPa) Hardness (HV) Min. Elongation
Class 10 ≥ 900 ≥ 1040 272–353 ≥ 9%

* Class 10 is the highest standard property class for carbon and alloy steel nuts per ISO 898-2, providing approximately 49% higher proof load stress than Class 8.

Why Choose FULLERKREG DIN 929 10B21 Weld Nuts?

  • 🏭 Factory Direct — Manufactured in-house with full process control from raw material to finished part
  • 💪 ISO Class 10 Strength — 10B21 boron steel delivers ≥1040 MPa tensile strength, the highest standard carbon steel class for weld nuts
  • 🔩 Automotive-Grade Material — 10B21 is the industry-standard material for high-strength weld nuts in automotive body-in-white (BIW) production
  • 📐 Strict DIN 929 Compliance — Every dimension and tolerance verified against the standard; no substitutions
  • 🔬 Material Certified — Mill test certificates (MTC) available; boron content and composition verified
  • 🎨 Bare Finish — Post-Process Ready — Uncoated surface is ideal for e-coat, powder coat, paint, or zinc plating applied after welding
  • ⚡ Excellent Weldability — Low carbon equivalent ensures consistent, reliable resistance welding performance
  • 📦 Bulk Wholesale Supply — MOQ-friendly pricing tiers; consistent lot quality for production lines
  • 🚢 Global Export Experience — Shipped worldwide with proper export documentation and packaging
  • 💬 Technical Support — Engineering team available for application guidance, custom sizes, and special requirements

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