M6 x 20mm Hexagon Head Set Screws – A2-70 Stainless Steel DIN 933

Reliable Stainless Steel Fastening for Engineering, Outdoor and Freshwater Applications

Our M6 x 20mm A2-70 stainless steel hexagon head set screws provide a durable, corrosion-resistant fastening solution for mechanical assemblies, construction projects and equipment exposed to freshwater environments.

Manufactured from A2 (304) stainless steel in accordance with DIN 933, these fully threaded hexagon bolts combine dependable mechanical strength with good resistance to moisture, atmospheric corrosion and many freshwater conditions.

Their compact 20mm length makes them particularly useful for securing brackets, metal plates, machinery components and fittings where a shorter fixing is required.

Technical Specifications

Specification	Details
Product Type	Hexagon Head Set Screw
Diameter	M6 (6mm)
Length	20mm
Thread Pitch	1.0mm Metric Coarse
Thread Type	Fully Threaded
Head Type	External Hexagon
Stainless Steel Grade	A2 / 304
Property Class	A2-70
Standard	DIN 933 / ISO 4017
Spanner Size	10mm
Minimum Tensile Strength	700 N/mm² (700 MPa)
Finish	Natural Stainless Steel

The 20mm length is measured from beneath the hexagon head to the end of the screw.

Can A2 Stainless Steel Bolts Be Used in Freshwater?

Yes. A2 (304) stainless steel is suitable for many freshwater applications, particularly where the water has relatively low chloride levels and temperatures remain moderate.

Unlike ordinary carbon steel bolts, A2 stainless steel contains chromium, which forms a thin protective oxide layer on the metal surface. This passive layer helps prevent corrosion and can naturally reform following minor surface damage when suitable conditions are present.

This makes A2 stainless steel a popular material for equipment exposed to rainwater, clean freshwater and general outdoor moisture.

However, not all freshwater environments are identical. Water chemistry, chloride concentration, temperature and whether water is flowing or stagnant can affect the long-term performance of stainless steel fasteners.

Freshwater Applications for M6 x 20mm Stainless Steel Bolts

These fully threaded stainless steel setscrews may be suitable for:

• Freshwater boating: Securing suitable fittings, brackets and equipment on boats operating in inland waterways
• Water treatment equipment: Fastening components in suitable low-chloride freshwater systems
• Irrigation systems: Assembling brackets, pump housings and associated equipment
• Lakeside installations: Fixing metal components exposed to freshwater spray and moisture
• Reservoir equipment: Securing non-critical fittings and maintenance components where the water conditions permit
• Rainwater harvesting: Fastening suitable components in collection and storage installations
• Outdoor machinery: Securing equipment regularly exposed to rain and damp conditions

For permanent immersion or safety-critical applications, the water chemistry and fixing design should be assessed before selecting the material.

Important Facts About A2 Stainless Steel in Freshwater

1. Chloride Levels Matter

A2 (304) stainless steel generally performs well in clean freshwater with relatively low chloride concentrations.

Industry guidance indicates that 304 stainless steel can be suitable in many flowing water systems with chloride levels below approximately 200 mg/L at normal water temperatures.

This is a general material selection guide, not a guarantee against corrosion in every installation.

2. Flowing Water Is Often Preferable to Stagnant Water

Stagnant water can encourage deposits and create local conditions that increase the risk of corrosion.

Correctly designed freshwater installations with good water circulation and limited deposits generally provide more favourable conditions for stainless steel.

3. Watch for Crevice Corrosion

Although A2 stainless steel resists general rusting, corrosion can develop in confined areas such