Stainless steel comes in many different grades. Each grade brings its own unique chemical composition, tensile strength, and other characteristics. Let’s take a look at two of the most popular grades of stainless steel — 430 and 304.
Like other forms of steel, stainless steel is an alloy of iron and carbon. What distinguishes stainless steel is the addition of chromium. To be considered stainless steel, the alloy must contain at least 10% chromium by weight. The chromium gives stainless steel its non-corrosive characteristics, which help lengthen the metal’s lifespan.
Kloeckner Metals is a full-line stainless steel supplier and service center. Check out our stainless steel spec sheet to see what Kloeckner Metals routinely stocks.
Carbon steel typically gets used for infrastructure, automobiles, and weapons. Stainless steel, by contrast, generally forms medical tools and food or beverage equipment. It tends to be brighter and more attractive than carbon steel.
The steel industry classifies metals by grades in order to ensure the consistency and quality that precise steel processing requires. A steel’s grade is determined by all the factors that make that steel unique.
Steel standards organizations determine how to classify each grade of steel. Because there are several standards organizations around the world, the same grade of steel may be classified differently across national boundaries. Grades 304 and 430 are American Iron and Steel Institute (AISI) standards.
Type 430 stainless steel is a mild, corrosion-resistant metal that can be easily bent, stretched, or drawn.
It features the following chemical composition:
Its relatively high carbon content and lack of stabilizing elements make this grade difficult to weld.
Type 430 stainless steel has a minimum yield strength of 30 ksi and a minimum tensile strength of 65 ksi. Most commonly, type 430 stainless steel is used in cosmetic applications that require more aesthetic appeal than strength. It is available in 430 stainless steel sheet.
Type 304 stainless steel is the most widely used of all stainless steel grades. It generally appears in kitchen equipment and industrial applications.
This grade of stainless steel features the following chemical composition:
Type 304 can be welded to plain carbon steel using TIG or MIG welding. This grade of stainless steel has a minimum yield strength of 30 ksi and a minimum tensile strength of 75 ksi.
This stainless steel grade is routinely stocked in various formats, including: 304 stainless steel sheet, 304 stainless steel plate, 304 stainless steel tube, and 304 stainless steel bar.
Stainless steel can be classified into three common categories — austenitic, ferritic, and martensitic.
Austenitic steel is the most common. It has a relatively high chromium content, making it especially corrosion-resistant and non-magnetic (although it may become magnetic after cold working).
Ferritic metals are the second most common category. These steels are less expensive than austenitic steels due to their lower nickel content. They are magnetic and can be hardened through cold working.
Martensitic stainless steel is the least common category of stainless steel. Although it is the hardest and most durable kind of stainless steel, martensitic metals are the least corrosion-resistant. Martensitic stainless steels are increasingly found in the automotive industry.
Type 430 stainless steel is ferritic while type 340 stainless steel is austenitic.
All grades of stainless steel resist corrosion, but grade 304 is particularly rustproof because of its high nickel content. This addition to the alloy makes grade 304 considerably more expensive than grade 430 stainless steel, however.
In general, grade 430 works best for budget-conscious buyers while grade 304 serves buyers with an eye for the long term.
Austenitic stainless steels are not magnetic. Since grade 304 stainless steel is austenitic, it is not magnetic.
Ferritic stainless steel grades are magnetic. Thus, grade 430 is magnetic. Most kitchen knives are made from the 400 grades of stainless steel, which is why they can be stored on a magnetic strip.
Stainless steel’s hardness is measured by the Brinell Hardness Number (BHN). The BHN is a measure of an alloy’s ability to resist permanent indentation.
Grade 430 stainless steel’s BHN is 183, and grade 304 stainless steel’s BHN is 201. The higher the BHN, the harder the alloy.
Each grade of stainless steel brings its own benefits and drawbacks. In general, grade 304 stainless steel offers more corrosion resistance than grade 430 because of its higher nickel content. The nickel also makes grade 304 easier to draw or press. That same element, however, also raises the price of grade 304 steel.
Put simply, grade 304 offers higher malleability and greater longevity, and grade 430 offers a less expensive steel option.
Grades 430 and 304 are the two most common grades of stainless steel. Both offer a durable iron alloy that can resist rust and corrosion. Typically, however, grade 304 provides more corrosion resistance and thus greater longevity than grade 430, which is a more budget-friendly option.
To find out which grade of stainless steel may be right for your project, contact Kloeckner today.
Kloeckner Metals is a full-line stainless steel supplier and service center. Kloeckner combines a national footprint with the latest fabrication and processing technologies and most innovative customer service solutions.
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