Hexagon Head Bolts - HDG, Hi - Tensile - (grade 8.8), DIN 931 / SABS - ISO 1461, M24 X 70 mm

Overview

DIN 931 defines a hexagon head bolt with a partially threaded shank. The standard covers the dimensional form of the bolt, including the hex head, threaded portion and plain shank, so that the fastener can be selected consistently by diameter, length and thread. The partially threaded design is useful where the smooth shank should pass through the joint to improve alignment and carry shear loads, while the threaded section provides the clamping force.

This selected size is specified with diameter M24, length 70 mm, thread M24, pitch 3 mm.

Sold in multiples of '10 pieces. 1 Box = '10 pieces.

Material, Grade & Strength

Grade 8.8 is a high tensile carbon-alloy steel property class commonly used for structural and mechanical bolting. The “8.8” designation indicates a nominal ultimate tensile strength of approximately 800 MPa and a yield strength of approximately 80% of that value, about 640 MPa. This makes it substantially stronger than ordinary mild steel fasteners and suitable for general engineering joints where higher clamp load and shear resistance are required. For critical assemblies, torque must be selected from a recognised torque chart using the actual thread size, pitch, lubrication condition, surface finish and mating nut grade. Use compatible high tensile nuts and washers rather than low-strength mild steel mating parts.

Finish & Corrosion Protection

Hot dip galvanising provides a thicker zinc coating than standard electroplating and is preferred for outdoor or exposed structural work where improved corrosion resistance is required.

Typical Uses

DIN 931 bolts are commonly used in machinery, fabricated steelwork, mining equipment, agricultural equipment, brackets, frames and maintenance work where a strong partially threaded bolt is preferred over a fully threaded set screw.

Technical Tips

• Use a matching nut and washer of the same thread size and suitable strength class.
• Where possible, position the plain shank through the shear plane of the joint rather than leaving threads in the shear area.
• For Grade 8.8, 10.9 or 12.9 bolts, use correctly rated mating nuts and washers.
• Torque values vary by diameter, pitch, finish and lubrication; always confirm the correct torque before use in safety-critical assemblies.
• For corrosion-sensitive applications, match the finish or material to the environment rather than relying only on strength grade.

Selection Advice

Choose DIN 931 when the joint benefits from a partially threaded shank. Choose DIN 933 when a fully threaded hexagon head set screw is required. Confirm diameter, length, thread, material, finish and grade before ordering.

Frequently Asked Questions

What is the difference between DIN 931 and DIN 933? DIN 931 is partially threaded, while DIN 933 is fully threaded. DIN 931 is often preferred where the plain shank assists alignment or shear performance.

Is Grade 8.8 stainless steel? No. Grade 8.8 normally refers to high tensile carbon-alloy steel. Stainless fasteners are usually specified by A2, A4 or a stainless property class.