High strength hex bolts are essential fasteners for steel structures, machinery, heavy equipment, construction projects, bridge components, and industrial assemblies. When buyers search for reliable fastening solutions, DIN933 full thread hex bolts and DIN931 partial thread hex bolts are two of the most commonly requested standards. Understanding the difference between these two standards, the bolt grades, surface treatments, and application conditions helps purchasing teams choose the correct product and reduce installation risk.
What are high strength hex bolts?
High strength hex bolts are bolts with a hexagonal head and a threaded shank, produced with higher mechanical strength than ordinary low-carbon steel bolts. They are usually selected when the connection must withstand vibration, shear force, tensile load, or long-term structural stress. Common strength grades include 8.8, 10.9 and 12.9, depending on the project requirements and engineering design.
DIN933 vs DIN931: which one should buyers choose?
DIN933 hex bolts are full thread bolts. The thread runs along the full length of the shank, making them suitable for applications where flexible clamping depth is needed or where the bolt passes through thinner plates. They are widely used in machinery assembly, equipment fixing, frame connection, and general industrial fastening.
DIN931 hex bolts are partial thread bolts. They have an unthreaded shank section under the head. This design can provide better shear performance in structural connections because the smooth shank can bear load more evenly in the joint area. DIN931 bolts are often used in steel structure, bridge, heavy machinery, tower, and construction projects.
Common grades: 8.8, 10.9 and 12.9
- Grade 8.8: widely used for construction, machinery, steel frames and general high-strength fastening.
- Grade 10.9: suitable for higher load applications, heavy machinery, automotive components and equipment assemblies.
- Grade 12.9: used for demanding mechanical applications where very high tensile strength is required.
When selecting the bolt grade, buyers should also confirm the matching nut grade and washer type. A high strength bolt should be used with compatible nuts and washers to keep the full fastening system safe and stable.
Surface treatment options for high strength hex bolts
The bolts shown in the photo use a black surface finish, which is common for high strength hex bolts. Depending on the application environment, buyers may also choose black oxide, plain black, zinc plated, hot dip galvanized, Dacromet, or other anti-corrosion coatings. For outdoor projects, humid areas, coastal environments, or chemical exposure, corrosion protection should be confirmed before ordering.
Key points before placing a bulk order
- Confirm standard: DIN933 full thread or DIN931 partial thread.
- Confirm grade: 8.8, 10.9, 12.9 or other project requirement.
- Confirm size: diameter, length, thread pitch and tolerance.
- Confirm surface: black, zinc plated, hot dip galvanized or custom coating.
- Confirm packing: carton, woven bag, pallet or customer label packaging.
- Confirm inspection requirements: material certificate, dimension inspection, hardness or tensile testing.
Why source high strength hex bolts from SHENHUI?
SHENHUI FASTENER supplies high strength hex bolts, threaded rods, nuts, washers, anchor bolts and custom fasteners for global customers. We support bulk orders, standard sizes, customized lengths, different surface treatments and export packaging. If you are sourcing DIN933 or DIN931 high strength hex bolts, send us your size list, grade, coating requirement and order quantity. Our team can help check specifications and provide a practical quotation for your project.