18/8 stainless steel is nominally 18% chromium and 8% nickel, with the remainder being mainly iron; it does however also contain other elements, but at very low levels.18-8 Stainless Steel is also known as type 302 or 304 grade stainless steel. This grade of stainless is generally regarded as one of the most common stainless steels as it is widely available. Stainless steel is an alloy of low carbon steel and chromium for enhanced corrosion characteristics. Stainless steel is highly corrosion resistant for the price and because the anti-corrosive properties are inherent to the metal, it will not lose this resistance if scratched during installation or use. Stainless steel does not stain, corrode, or rust as easily as ordinary steel, but it is not stain-proof. It is also called corrosion-resistant steel or CRES when the alloy type and grade are not detailed, particularly in the aviation industry. Stainless steel fasteners are used where both the properties of steel and resistance to corrosion are required.
It is a common misconception that stainless steel is stronger than regular steel. In fact, due to the low carbon content, stainless steel cannot be hardened. Therefore, when compared with regular steel, it is slightly stronger than un-hardened (grade 2) steel bolts and other fasteners, but significantly weaker than hardened steel fasteners. Stainless steel fasteners are also much less magnetic than regular steel fasteners though some grades will be slightly magnetic.
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300 Series austenitic chromium-nickel alloys
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Type 302 has the same corrosion resistance as 304, with slightly higher strength due to additional carbon.
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Type 304 is the most common grade; the classic 18/8 stainless steel. Outside of the US it is commonly known as "A2" Stainless. (see our Stainless Steel Metric Fasteners)
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Type 316 is the second most common grade (after 304); for food and surgical uses; alloy addition of molybdenum prevents specific forms of corrosion. It is also known as marine grade stainless steel due to its increased resistance to chloride corrosion compared to type 304
Important: Please read article on Galling
