Hexagon bolt | A4 | DIN 933
Do you need a machine screw that works safely even in humid, salty, or chemically demanding environments? Hexagon head screw in A4 / AISI 316 acid-proof stainless steel according to DIN 933 is built to withstand heavy corrosion and maintain strength over a long period. It combines high breaking strength with reliable durability and is optimized to handle high mechanical loads and frequent use.
APPLICATION AREAS
Perfect for fastening in marine environments, coastal construction, piers, boats, the food industry, and chemical plants where high corrosion resistance is a requirement. The fully threaded construction provides a stable and vibration-resistant connection. Easy to install with a socket wrench or open-end wrench and requires minimal maintenance even during continuous operation.
Watch video: Tightening torque for stainless steel screws
TECHNICAL SPECIFICATIONS
Product type: Hexagon screw / bolt
Standard: DIN 933 (corresponds to ISO 4017)
Quality: A4 / AISI 316 (acid-proof stainless steel)
Material class: A4-70 (other classes on request)
Thread type: Metric, fully threaded
Surface treatment: Untreated (natural stainless steel)
Head shape: Hexagon
Drive type: Not applicable
FREQUENTLY ASKED QUESTIONS (FAQ)
What does it mean that the screw is manufactured according to DIN 933 and is fully threaded?
DIN 933 (corresponds to ISO 4017) is the German standard for hexagon head screws with thread all the way up to the screw head. The fully threaded design makes the screw extremely versatile, as it can be threaded all the way into a threaded bottom hole or used together with a nut for clamping components regardless of material thickness.
Why is acid-proof A4 / AISI 316 required in salty and chemically demanding environments?
Acid-proof A4 steel (AISI 316 / 1.4401) is alloyed with molybdenum, which provides exceptionally strong resistance to pitting and stress corrosion. This makes the screw completely resistant to chlorides, saltwater, exhaust gases, and industrial chemicals – unlike standard A2 steel, which risks corroding over time in marine or highly acidic environments.
Which accessories should be used during installation to maintain corrosion protection?
To avoid galvanic corrosion and ensure a homogeneous joint, the screw should always be installed with nuts (e.g., DIN 934) and washers (e.g., DIN 125 or DIN 9021) in matching acid-proof A4 quality. For high tightening torques or frequent installation, assembly paste is also recommended to prevent stainless steel threads from seizing (galling).