DIN 931 is the prestigious German industrial standard for hexagon head bolts with a Partially Threaded shank. This design features an unthreaded portion (the "grip length") between the head and the threads, making it the primary choice for structural joints requiring high shear strength and precise alignment.

As a cornerstone of European mechanical engineering, DIN 931 ensures consistent dimensions and mechanical performance across international supply chains, particularly in automotive, infrastructure, and industrial plant construction.

The unthreaded shank of a DIN 931 bolt is designed to sit within the shear plane of the connected parts. Since the shank has a larger cross-sectional area than the threaded root, it can withstand significantly higher lateral forces without yielding. This structural "partial thread" logic is essential for assemblies subject to dynamic loads where thread-root stress concentration must be avoided.