About Cap Screw Materials
Grade/Class
Features
Grade 2 See Titanium under Material Type.
Grade 5 Made of medium-strength steel.
Grade 8 Made of high-strength alloy steel.
Grade 9 Made of high-grade alloy steel.
Grade CU2 See Brass under Material Type.
Class 8.8 Made of medium-strength, heat-treated steel.
Class 10.9 Made of high-strength steel.
Class 90 and 100 Both are stronger than Grade 5.
Finish/Coating
Features
Plain For general purpose applications. A good economical choice.
Zinc-Plated Provides excellent corrosion resistance.
Cadmium-Plated Offers better rust resistance than zinc-plating, especially in salt environments.
Black Offers mild rust resistance and some lubricity.
Black Luster-Coated Offers a durable and decorative finish. Provides corrosion resistance superior to black and zinc-plated finishes.
Blue-Coated This highly visible blue coating makes it easier to distinguish from inch sizes.
Hot-Dipped Galvanized Same strength and properties of zinc-plating, but with a thicker coating for excellent rust, weather, and corrosion resistance.
Ultra Corrosion-Resistant Coated Have a silver, water-based inorganic coating (also known as armor coat) for excellent corrosion resistance.
Material Type
Features
Steel Good for general purpose applications.
Alloy 20 Stainless Steel Also known as Carpenter 20, it's nonmagnetic and especially resistant to stress corrosion.
17-4 PH Stainless Steel Combines the high-strength of alloy with corrosion resistance of stainless steel.
18-8 Stainless Steel Offers excellent corrosion resistance; it may be mildly magnetic.
300 Stainless Steel Meet more stringent specifications such as military specifications. All are passivated (a nitric acid treatment that creates a passive film to protect the stainless steel from oxidation and corrosion).
316 Stainless Steel Offers even better corrosion than 18-8 stainless steel. It contains molybdenum, which increases resistance to chlorides and sulfates. It may be mildly magnetic.
450 Stainless Steel Offers more corrosion resistance than alloy steel.
Aluminum Alloy 2024-T4. Has good resistance to corrosion caused by weather. It's nonmagnetic and offers the strength of mild steel at one third the weight.
Brass Softer than steel with good corrosion resistance. Nonmagnetic.
Nickel-Copper Alloy 400 (Monel) Also known as Monel. Has exceptional strength and resistance to heat and corrosion. Slightly magnetic. Especially well suited for use near salt water.
Fiberglass Made of polyurethane reinforced with fiberglass for greater strength than nylon.
Kynar Possesses excellent corrosion and chemical resistance. Also known as PVDF (polyvinylidene fluoride), it's a tough and durable material.
Nylon 6/6 This nonconductive material resists chemicals and solvents, except mineral acids.
PTFE Has high dielectric properties, so it's perfect for electrical applications. Resists moisture and chemicals, and has excellent mechanical properties.
PVC Provides excellent corrosion resistance against weak acids, alkalies, and alcohols.
Silicon Bronze Alloy 651. Nonmagnetic. Made of 95-98% copper plus silicon for added strength, it offers high corrosion resistance against sea water, gases and sewage.
Titanium Grade 2. Outstanding corrosion resistance. As strong as steel at 57% of the weight. It is nonmagnetic and has excellent temperature resistance.
A286 Super Alloy An iron-based material containing 26% nickel and 15% chrome. It offers the strength of alloy steel with corrosion resistance similar to 18-8 stainless steel.