Stainless Steel : A2 vs A4 – a simple guide Chemical Composition A2 : Often referred to as 304 or 18 / 8 stainless . 18 / 8 refers to the amount of chromium and nickel in the alloy – 18 % chromium and 8 % nickel , the chromium provides a corrosion and oxidation resistance , however it can be prone to tarnishing .
Huck Magna-Lok Cross Section - Uninstalled and Installed
A4 : often referred to as 316 , 18 / 10 and marine grade stainless . 18 / 10 refers to the chromium and nickel content- 18 % chromium and 10 % nickel , and 2-3 % molybdenum . The molybdenum increases the corrosion resistance to withstand attack from many solvents , for example , sulfuric acid , chlorides , de-icing salts and industrial chemicals . It is considerably more resistant to solutions of bromides , iodides and fatty acids at high temperature .
Corrosion Resistance A2 ( 304 ): Offers good corrosion resistance in most environments , but not as resistant as A4 in corrosive environments like marine or chloride-rich settings . A4 ( 316 ): Provides excellent corrosion resistance , particularly in chloride environments like marine settings or industrial areas with exposure to chemicals .
Strength and Durability A2 ( 304 ): Offers good strength and toughness suitable for many general-purpose applications . A4 ( 316 ): offers the same strength characteristics as A2 but it is more corrosion resistant in demanding environments .
Both A2 and A4 grades are classed as Austenitic stainless steel ( sometimes called the 300 series ). This means that they have high chemical resistance but cannot be hardened by heat treatment . They can be hardened by cold working .
Molybdenum Content A2 ( 304 ): Does not contain molybdenum .
A4 ( 316 ): Contains molybdenum which enhances its corrosion resistance .
Stainless steel may also contain other alloying elements such as nickel , titanium , copper and manganese , among others , to enhance specific properties like strength , corrosion resistance , and durability . Non-metal additions are also made , the main ones being Carbon and Nitrogen . The exact composition and properties of stainless steel can vary depending on the specific grade or type .
Common Properties of A2 and A4 Stainless Steel
While A2 ( 304 ) and A4 ( 316 ) stainless steels share common properties , their differences in composition , particularly the addition of molybdenum in A4 ( 316 ), result in variations in corrosion resistance and mechanical properties . As a result , the selection between A2 and A4 stainless steel depends on the specific application requirements , particularly the level of corrosion resistance needed .
In summary , while both A2 ( 304 ) and A4 ( 316 ) stainless steels offer corrosion resistance and are widely used , the choice between them depends on the specific application requirements . A4 ( 316 ) is generally preferred for applications where superior corrosion resistance , particularly in harsh environments is essential .
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Issue 68 PECM 17