Square Weld Nuts (DIN 928) – 10B21 Medium-Strength Alloy Steel, ISO Class 8, Bare Finish

FULLERKREG DIN 928 square weld nuts in 10B21 boron alloy steel at ISO class 8 strength offer significantly higher proof load and tensile strength than standard class 4 low carbon steel variants, making them the preferred choice for high-load structural assemblies, heavy equipment, and safety-critical sheet metal joints. The 10B21 boron-treated alloy steel delivers excellent hardenability and consistent mechanical properties after heat treatment, while maintaining good weldability for resistance projection welding. The bare (uncoated) finish ensures optimal electrical conductivity during welding and maximum adhesion for subsequent e-coat, powder coat, or paint processes. Four precision weld projections on the bearing face concentrate heat for consistent, high-strength weld joints. The square body provides excellent anti-rotation resistance in the parent material.

Product Specifications

Dimensional Data

All dimensions in millimeters (mm). Weight per 1000 pcs in kg. Unit weight (g/pc) calculated from standard data. Refer to diagram: A = body width across flats, C = body thickness, D = thread diameter, H = projection height, E = projection diameter, F = projection pitch circle diameter.

Note: Dimensional data per DIN 928 standard. Weights based on 10B21 alloy steel density (7.85 g/cm³). Actual weights may vary slightly by batch.

Mechanical Properties – ISO Class 8 / 10B21

Class 8 vs Class 4 – Strength Comparison

About 10B21 Boron Alloy Steel

10B21 is a boron-treated medium carbon alloy steel widely used in high-strength fastener manufacturing. The addition of boron (0.0005–0.003%) dramatically improves hardenability — allowing the steel to achieve class 8 strength through quench and temper heat treatment while maintaining a relatively low carbon content. This results in:

• High strength-to-weight ratio – Class 8 proof load at compact weld nut geometry
• Good weldability – Lower carbon equivalent than conventional medium carbon steels
• Consistent hardenability – Boron ensures uniform through-hardening across production batches
• Cost efficiency – Achieves alloy steel performance at near-carbon-steel material cost

Welding Guide

Selection Guide

Standard Reference

DIN 928 specifies square weld nuts with metric threads and four weld projections, issued by the Deutsches Institut für Normung (DIN). The standard defines body dimensions, projection geometry, and thread tolerances for resistance welding applications. FULLERKREG manufactures these class 8 weld nuts in 10B21 boron alloy steel with strict conformance to DIN 928 dimensional tolerances. The bare finish is specified for assemblies where post-weld surface coating is applied as part of the production process.

Product Gallery

DIN 928 Class 8 10B21 Alloy Steel Bare Square Weld Nuts – actual product photos

Why Choose FULLERKREG?

🏭 Direct Manufacturer – Factory-direct pricing with full dimensional traceability
📐 DIN Precision – Strict conformance to DIN 928 tolerances, projection geometry verified by QC
💪 ISO Class 8 Strength – 800 MPa proof load for high-load structural and safety-critical joints
⚡ Weld-Ready Projections – 4 precision projections ensure consistent resistance weld quality
🔬 10B21 Boron Alloy – Superior hardenability and strength-to-weight ratio vs plain carbon steel
🎨 Bare Finish – Optimal for post-weld e-coat, powder coat, or paint processes
✅ RoHS Compliant – All products meet EU RoHS environmental directives
📦 Bulk Wholesale Ready – MOQ flexible, available in bags, boxes, or bulk cartons
🌍 Global Shipping – Reliable export logistics to Europe, North America, Southeast Asia
💬 Technical Support – Engineering team available for welding parameters and substitution queries