Stainless steel socket screws are noted for their superior corrosion resistance, available primarily in A2 (Grade 304) and A4 (Grade 316) stainless steel.
Grades and Corrosion Resistance
The primary distinction in stainless steel socket screws is their grade, which determines their chemical composition and suitability for different environments.
- A2 Stainless Steel (Grade 304): This is the standard, general-purpose grade.
- Composition: Contains approximately 18% chromium and 8% nickel.
- Corrosion Resistance: Offers good resistance to corrosion in most environments, ideal for general indoor and outdoor use, and freshwater applications.
- Applications: Commonly used in kitchen equipment, food processing, and architectural trim.
- A4 Stainless Steel (Grade 316): Often referred to as "marine grade" stainless steel.
- Composition: Contains about 16% chromium, 10% nickel, and crucially, 2-3% molybdenum.
- Corrosion Resistance: The addition of molybdenum provides superior resistance to pitting and crevice corrosion, especially in chloride-rich or harsh chemical environments like saltwater, swimming pools, and chemical plants.
- Applications: Ideal for marine hardware, coastal structures, and applications involving aggressive chemicals.
Product Types
Stainless steel socket screws are available in various head designs to suit specific installation and aesthetic requirements.
- Socket Head Cap Screws: The most common type, featuring a cylindrical head with a deep internal hex drive (Allen key). They are used where a strong, wrench-tightened connection is needed.
- Socket Button Head Screws: These offer a smooth, low-profile, dome-shaped head for a clean finish and are typically used for light-duty applications.
- Socket Countersunk Head Screws: Designed to sit flush within a pre-drilled hole, providing a smooth, flat surface finish.
- Socket Set Screws: These are headless screws, also known as grub screws in the UK, used to secure an object against another, such as a pulley on a shaft.
