Partially threded Allen bolt
Half-threaded Allen bolts are manufactured from carbon steel or stainless steel and feature partial threading to withstand high torsional and tensile forces. Their diameters typically range from 4 to 20 millimeters, with lengths varying between 10 and 150 millimeters. These bolts are produced according to DIN 912 or ISO 4762 standards, with common strength grades including 8.8, 10.9, and A2-70 for stainless steel. The bolt head angle is usually 90 degrees, and head types are designed as cylindrical or button heads. Surface treatments such as galvanizing or phosphating enhance corrosion resistance and extend service life.
The half-thread design means only part of the bolt’s length has threads, increasing fatigue resistance and reducing damage risk in joints. Thread pitch ranges from 0.7 to 2.5 millimeters, conforming to ISO and DIN standards. Dimensional tolerances are controlled within ±0.15 millimeters, and surface hardness improves to 35–45 HRC through heat treatment. These bolts are widely used in automotive, heavy machinery, and metal structure industries. Their half-thread structure enables more precise and stable fastening.
