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​A2 vs A4 Stainless Steel Fasteners

30th Nov 2023

18-8 (A2) vs 316 (A4) Stainless Steel Fasteners

When choosing the correct fasteners for a project, understanding the features and differences between them is vital for safety reasons. Two of the most commonly used materials for fasteners are 18-8 (A2) and 316 (A4) stainless steel. Both have unique properties that make them ideal for specific applications, but which one is right for your project? Today, we'll compare and contrast 18-8 and 316 stainless steel fasteners, highlighting their properties, uses, and how to identify them so you can make the best choice for your next project.

Properties of 18-8 (A2) Stainless Steel Fasteners

18-8 stainless steel, also known as type 304 or A2 stainless steel, is an austenitic alloy with a mix of characteristics, making it ideal for many applications. It is named 18-8 due to its composition—approximately 18% chromium and 8% nickel, along with iron and other elements.

18-8 stainless steel fasteners are well-known for their high corrosion resistance, especially in normal weather or atmospheric conditions. They're durable, with high tensile and yield strength, making them suitable for general use in many different environments. 18-8 fasteners are most commonly seen in appliances, construction, and general engineering applications. For identification, look for the markings of "A2" or "304"

Properties of 316 (A4) Stainless Steel Fasteners

316 stainless steel, also known as A4 or marine grade stainless steel, is another popular choice in the realm of fasteners. Like its 18-8 counterpart, 316 is an austenitic alloy with additional elements—most importantly, 2-3% molybdenum.

The addition of molybdenum greatly improves resistance to chloride corrosion, making 316 fasteners the best choice for highly corrosive environments such as marine or chemical processing industries. 316 can withstand exposure to saltwater, certain acids, and high temperatures much better than 18-8 fasteners. In terms of identification, look for the markings of "A4" or "316".

Difference Between 316 (A4) and 18-8 (A2) Stainless Steel

The main difference between 18-8 and 316 stainless steel is that their different compositions will determine the corrosion resistance. Both are austenitic, but 316 includes molybdenum, a key element that will boost the resilience against corrosive substances, particularly chlorides. This makes 316 a greater choice for those environments where exposure to corrosion such as in saltwater environments is of concern.

Lastly, 316 stainless steel has a higher resistance to high temperatures and acids. While both types of stainless steel are suitable for many applications, the type of environment where the fasteners are used should be the determining factor for which steel is best.

Browse Our 316 and 18-8 Stainless Steel Fasteners

At ASMC, we offer a wide range of 18-8 and 316 stainless steel fasteners suitable for a variety of applications. We understand the need for quality and durability, which is why our products are designed to meet your high standards. So, whether you're working on a marine application that requires 316's superior corrosion resistance or a general project where 18-8's durability is ideal, we've got you covered. Browse through our selection today or contact us for a quote. Let us help you find the perfect fastener solution for your needs.