300 Series vs. 400 Series Stainless Steel: Key Differences to Keep in Mind

Stainless steel in various steel grades

Stainless steel is an important building material in industries across the world. If you’re already confident that stainless steel is proper type of steel for your project, the next step is to understand how stainless steel grades can differ and what unique qualities they can offer for different projects.

Today, the steel experts at Pennsylvania Steel Company, which offers products such as tool steel, sheet steel, and plate steel, are breaking down two of their most popular grades, 300 series stainless steel and 400 series stainless steel. Keep reading to learn what makes them different and which you should choose for your project.

What are Stainless Steel Grades?

Stainless steel, at its basic level, is an alloy of chromium and iron. In addition to these metals, stainless steel may also include elements like: 

  • Carbon
  • Nickel
  • Manganese
  • Nitrogen
  • Sulfur
  • Copper

Stainless steel grades are determined by which elements they contain and the percentage of each present. Based on this, the alloy can take on different properties that make it suited for various applications.

The Society of Automotive Engineers (SAE) developed the three-digit grading system for stainless steel to reflect the elements present. 300 series and 400 series contain varying compositions reflected by the last two digits in the grade.

Other organizations, like the American Society for Testing and Materials (ASTM), have their own numbering systems to categorize stainless steel. But this article will focus on the three-digit classification for simplicity.

While over 150 stainless steel grades are available on the market, Pennsylvania Steel Company specializes in 300 series and 400 series stainless steel.

Although all stainless steel offers high durability and resistance to rust and corrosion, there are some critical differences between the 300 series and 400 series that you should remember when choosing which is suitable for your project.

What is 300 Series Stainless Steel?

300 series stainless steel, also called SS 300, is the most popular stainless steel grade on the market. Due to its nickel content, SS 300 is non-magnetic and highly corrosion-resistant – even more so than other stainless steel grades. It also has high heat resistance, making it ideal for use in industries like:

  • Automotive production
  • Aerospace engineering
  • Construction
  • Machinery

While 300 series stainless steel is not heat-treatable like other grades, its high versatility makes it an excellent choice for projects that need to withstand long stretches of use in corrosive environments.

What is 400 Series Stainless Steel?

400 series stainless steel, or 400 SS, is made with little to no nickel content compared to its 300 series counterpart. While this makes it susceptible to rust under certain conditions, it also gives it superior toughness and resistance to damage from wear and abrasions.

400 SS used to make kitchen equipment

Because of its robustness and high durability, 400 SS finds much of its use in:

  • Tools
  • Kitchens and culinary services
  • Agriculture
  • Furnaces

 While it lacks the top-shelf rust resistance of the 300 series, 400 series stainless steel is both heat-treatable and magnetic, making it ideal for manufacturing objects that experience daily use and manipulation.

300 vs 400 Series Stainless Steel

Now that we’ve looked at what makes them unique, let’s review how 300 series and 400 series stainless steel grades compare side-by-side.

Composition

300 series contains nickel, making it more resistant to corrosion. 400 series has a higher carbon content, which makes it more resilient but more prone to rust.

Strength

300 series is more ductile than the 400 series and has less resistance to surface wear and tear. This makes the 300 series more suitable for sensitive applications like surgical instruments or machinery, whereas the 400 series’ hardness makes it ideal for hand tools or agricultural use.

Price Point

The 300 series is not heat-treatable, so it can be more expensive to manufacture. Due to this, the 400 series can be a more cost-effective option when there is a lower risk of exposure to corrosive elements.

Let Pennsylvania Steel Company Build with You!

Pennsylvania Steel Company has been a trusted provider of stainless steel products for over 50 years. Our company is dedicated to providing total care and attention to each customer’s needs, and we offer next-day service in most of our locations. 

If you’re ready to begin your next project, request a quote online or call one of our distributors in Pennsylvania; Bethpage, NY; Naugatuck, CT; Cleveland, OH; Stanley, NC; or Ashland, VA for more information about our wide variety of 300 series and 400 series stainless steel products!

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