Steel vs Stainless Steel: Choosing the Right Fastener Material

If you’re unfamiliar with the term, fasteners are hardware devices used to affix or “fasten” two objects together, and they’re the umbrella term for nuts, bolts, screws, and the like. While it’s important to know which type of fastener should be used with certain projects, it’s just as important to know the types of materials. People who are inexperienced or untrained would often choose fasteners by their type and size, but rarely consider the type of material the particular fasteners are made of. The two most common of which is steel and stainless steel, and it’s important to know the difference between the two to choose the right one for the job:

Steel

Steel is the most common material used for making fasteners, comprising up to 90% of all fasteners manufactured annually. Steel isn’t just durable, but it’s also quite inexpensive making it the most popular fastener material of choice. When you go to your local hardware store, you may notice the different “grades” in the steel fasteners being sold, and it’s also important to know these distinctions:

Grade 2. These are standard-grade or “unhardened” steel and oftentimes feature the manufacturer’s mark.

Grade 5 or F. These are hardened for increased strength and are generally used for in automotive application. Bolts with this grade have three evenly-spaced lines on its head.

Grade 8 or G. These are hardened further to be used for more demanding applications. Bolts with this grade have six radial lines on its head.

Alloy Steel. Alloy steel are distinguished by their greyish black finish, and are further heat-treated. They can be strong but also brittle due to the heat treatment.

Steel fasteners are also available in non-coated/plain options, but they also come in different coatings, namely:

Zinc Plating. Fasteners undergo electroplating with zinc to increase its corrosion resistance and provide it with a glistening appearance, but isn’t recommended for marine environment.

Hot Dip Galvanizing. Galvanising involves applying a layer of zinc by immersing the fastener in molten zinc. This adds a thick layer of zinc with superior corrosion resistance.

Chrome-Plated. Chrome plating provide a polished appearance as well as corrosion resistance similar to zinc plating, but chrome is much more expensive.

Stainless Steel

When it comes to fasteners, stainless steel is the other go-to material being used, and for good reason: it’s highly resistant to corrosion and lasts longer. However, there’s a common misconception that stainless steel is a lot stronger than regular steel, but this isn’t the case — stainless steel alloys can’t be hardened through heat treatment due to its low carbon content, which means that it’s weaker than hardened steel fasteners but still relatively stronger than un-hardened (or Grade 2) steel. One should also be aware of the variations of stainless steel:

18-8 Stainless. The name refers to the ratio of chromium to nickel: 18% chromium and 8% nickel, and is regarded as the most common variant.

Stainless 316. These types of stainless steel fasteners are highly resistant to corrosion and work well in salt water and chlorine environments, making them ideal in marine vessels and other structures or vehicles used at or near the sea.

Stainless 410. These are oftentimes used for highly stressed parts as they have higher strength and hardness than 18-8 stainless steel but doesn’t have the same level of corrosion resistance.

Conclusion

Fasteners organized in containers

Steel and stainless steel are two of the most commonly used materials for fasteners, although there are other materials used for specific applications. It’s apparent that these two have their strengths and variations, and it’s important to know each distinction. So the next time you’re looking up fasteners with your local hardware store or your repair/service business’ bolts and nuts suppliers, it’s best to be wary of the material used and not just the size and type of fastener to get the best results.

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