316 Stainless vs 18/8 Socket Cap Screws: Which to Choose?
By Mutual Screw & Supply | Published: 2026-10-24
Category: Comparisons
Compare 316 stainless steel and 18/8 stainless steel socket cap screws to find the right balance of corrosion resistance, strength, and cost for your project.
Quick answer
Choose 316 stainless steel socket cap screws for marine or high-corrosion environments; choose 18/8 stainless steel for general-purpose indoor use where cost matters more.
Corrosion resistance: 316 vs 18/8
316 stainless steel contains molybdenum, which gives it superior resistance to chlorides and saltwater compared to 18/8 (304) stainless steel. This makes 316 the go-to choice for coastal, marine, or chemical-exposed assemblies.
18/8 stainless steel offers good corrosion resistance for most indoor and mild outdoor conditions, but it can pit or stain when exposed to salt spray or harsh chemicals over time.
Strength and mechanical properties
Both 316 and 18/8 stainless steels have similar tensile and yield strength in the annealed condition. However, 316 can maintain its strength at higher temperatures and retains more toughness in cryogenic conditions.
For most fastening applications at room temperature, the strength difference is negligible. The real distinction is corrosion performance, not load capacity.
Cost and availability
316 stainless steel is significantly more expensive than 18/8 due to its alloying elements. If your project does not require marine-grade corrosion resistance, 18/8 provides a more budget-friendly option.
18/8 socket cap screws are also more widely available in common sizes and pack quantities, making them easier to source for quick repairs or large orders.
316 vs 18/8: trade-offs at a glance
- Corrosion resistance: 316 stainless steel has superior resistance to chlorides and saltwater due to molybdenum content. 18/8 is adequate for dry indoor or mild outdoor use. If your fastener will be exposed to salt, chemicals, or constant moisture, choose 316.
- Strength: Both materials offer similar tensile strength at room temperature. 316 retains strength better at high or low temperatures.
- Cost: 316 stainless steel costs more due to its alloying elements. 18/8 is more budget-friendly and widely available in common sizes. For projects where corrosion risk is low, 18/8 saves money without sacrificing performance.
Product facts
- 5/16-18 X 1-3/4" Socket Cap Screws | Button Head Hex Socket Drive | Fully Threaded | 316 Stainless Steel (100 / Pkg.): These 5/16-18 x 1-3/4" socket cap screws are manufactured from 316 Stainless Steel, featuring a hex socket drive. 316 stainless steel provides the highest corrosion resistance among common stainless fasteners, ideal for marine, chemical, and outdoor applications.
5/16-18 X 1-3/4" Socket Cap Screws | Button Head Hex Socket Drive | Fully Threaded | 316 Stainless Steel (100 / Pkg.) - M5-0.8 X 20mm Socket Cap Screws | Hex Socket Drive | Fully Threaded | 18/8 Stainless Steel (400 / Pkg.): These M5-0.8 x 20mm socket cap screws are manufactured from 18/8 Stainless Steel, featuring a hex socket drive. 18/8 stainless steel offers reliable corrosion protection for indoor machinery and assemblies at a lower cost than 316.
M5-0.8 X 20mm Socket Cap Screws | Hex Socket Drive | Fully Threaded | 18/8 Stainless Steel (400 / Pkg.)
Which one fits your project?
Best for
- Marine and coastal applications where saltwater exposure is constant
- Chemical processing, food service, or outdoor equipment requiring maximum corrosion resistance
Not ideal for
- Indoor machinery or dry assemblies where 18/8 stainless steel provides sufficient corrosion protection at a lower cost
