What is the Difference between A2 and A4 Stainless Steel Fasteners?

A2-70 and A4-70 fasteners have a lot in common, but their differences are crucial. These are austenitic stainless steel. Both are low-carbon and have good corrosion resistance. Both are non-magnetic and have high ductility and good weld-ability, making them popular for use in manufacturing.

However, A2-70 Bolts have better machinability than A4-70, making them easier to work with. Both can be hardened by cold working, but A4-70 has the additional advantage of being able to be hardened by heat treatment as well.

A2 and A4 materials are grades of stainless steel. Both grades exhibit the same strength, ductility, and toughness as ordinary steel, but can withstand corrosion because of their chromium content.

A2 material has a chromium content of approximately 10.5% and can be heat treated to increase its toughness. It is more corrosion resistant than A4 material, but less so than ordinary steel. For this reason, it is most commonly employed in applications where corrosion resistance is required without being a primary concern.

A4 material has a chromium content of approximately 18%, making it more corrosion-resistant than A2 material and ordinary steel. Because of its high corrosion resistance, it is the preferred grade for marine-grade applications.

These materials are cold worked austenitic stainless steels, and they are available in several subgrades, such as A2-70 and A4-80. Generally, the numbers designate the minimum tensile strength of the component in MPa, for example, In addition to their high-temperature resistance, both A2 and A4 have minimum tensile strengths of 700 MPa and 800MPa, respectively.

In contrast, high temperatures can produce the precipitation of chrome carbide, which reduces the materials’ corrosion resistance. On the other hand, heated and cooled materials are harder and more resistant to corrosion, allowing them to be used in food processing, transportation, and other industries.

The A2 grade is a more general-purpose material that may be utilized in household and broad corrosive duty applications. A4 is a higher grade of stainless steel than A2 or A3 and is suitable for use in more corrosive environments, such as ocean water, saltwater, and food-grade and surgical devices.