300 vs. 400 Series Stainless Steel: A Comprehensive Comparison

Stainless steel comes in many grades to meet the unique requirements of their intended application. The most common families of stainless steel are 300 and 400 series stainless steel. These grades can be cut into specific shapes and sizes and finished according to your project’s needs. AAA Metals distributes 300 series, 400 series, and other stainless steel grades, as well as titanium, nickel alloys, and hard-to-find metals. We serve numerous industries with our high-quality alloys, including the aerospace, chemical, marine, packaging, and pharmaceutical sectors.

Read on to learn more about the benefits of 300 and 400 series stainless steel, their respective chemical compositions, and their common applications.

Understanding the 300 and 400 Series

Depending on the performance requirements of your project, various grades of stainless steel are available to meet these needs. If it requires durability, 300 series and 400 series stainless steel are preferred choices.

300 series stainless steel (SS 300) is the most popular type, offering excellent corrosion resistance and non-magnetic properties due to its higher nickel content. 400 series stainless steel (SS 400) contains less nickel than SS 300, but it offers improved abrasion resistance and toughness compared to SS 300. However, SS 400 can be more susceptible to oxidation and rust under certain environmental conditions.

To compare the benefits of 300 and 400 series stainless steel side by side, see the following key characteristics:

• 300 Series Stainless Steel:
  • Exceptional machinability
  • Austenitic crystalline structure with non-magnetic properties
  • High-temperature resistance
  • Multiple finishing options
  • Simple maintenance
  • Crack, scratch, and etch resistance
  • Resistance to thermal shock
  • High creep resistance
  • Resistance to carburizing and nitriding
• 400 Series Stainless Steel:
  • Improved strength compared to carbon steel
  • Martensitic crystalline structure with magnetic properties
  • Various surface finishing options
  • Not hardenable with heat treatment
  • A sustainable option for applications requiring thin, lightweight materials
  • Resistance to high-temperature scaling

Chemical Composition and Properties

The chemical composition of stainless steel is primarily iron with a chromium content of 10.5% or more. The chromium content allows every grade of stainless steel to develop a passive chromium oxide layer on its surface, providing excellent resistance to corrosion.

300 series stainless steel has a chemical composition of iron, nickel, 16-26% chromium, 2% manganese, up to 4% molybdenum, and trace amounts of other elements. 400 series stainless steel is typically composed of iron, 11-27% chromium, around 1% manganese, and trace amounts of other elements. SS 400 has a higher carbon content than SS 300.

Common Applications of Each Series

300 and 400 series stainless steel offer a suitable solution for numerous applications. Some of the common industries and applications where grades of 300 series stainless steel are used include:

• 303 Stainless Steel: aerospace nuts, gears, bolts, and fittings
• 304 Stainless Steel: shipping, food and beverage, nuclear, and automotive industries
• 304L Stainless Steel: welding applications
• 316 Stainless Steel: marine and nuclear applications
• 316L Stainless Steel: chemical and pharmaceutical industries

Specific grades of 400 series stainless steel are ideal for the following applications:

• 416 Stainless Steel: washing machine components, studs, valves, gears, and pumps
• 440C Stainless Steel: bearings, surgical instruments, and nozzles

Contact AAA Metals for Custom Stainless Steel Solutions

300 and 400 series stainless steel grades offer excellent durability and resistance to corrosion for most applications, from stainless steel fittings to gears to surgical instruments. AAA Metals can help you select the ideal stainless steel grade for your application. We have over 40 years of experience in the metals industry serving customers with prompt delivery, quality materials, and competitive pricing. We supply raw materials in plate, bar, ring, disc, pipe, tubing, and other forms and can polish or precision-cut them to your specifications.

Contact us or request a quote to connect with an expert about your stainless steel needs.