Stainless Steel Grades: All About 304

Steel is one of the most widely used materials in the world, useful for creating an infinite variety of different structures and components. Primarily composed of carbon and iron, steel can be further alloyed with a range of other elements to create a vast family of steel types. One of these elements is chromium: when chromium is added to steel, it results in stainless steel.

Within the stainless steel family, there are numerous different types and grades. By far the most common grade is 304, which accounts for more than 50% of the stainless steel used around the world. 304 grade stainless steel is austenitic, a term which relates to its molecular structure and signifies that nickel has been added to the alloy. Austenitic stainless steels are the most common; as much as 70% of commercially-produced stainless steel is of the austenitic type.

Stainless steel of grade 304 is composed primarily of iron, which makes up between 66% and 75% of its composition. Also included in the alloying mix is between 18% and 20% chromium and between 8% and 10.5% nickel. With a density measured at around eight grams per cubic centimetre, 304 stainless steel may also contain trace amount of other elements like silicon, sulphur , phosphorus and manganese.

As standard, 304 stainless steel has around 0.08% carbon content. 304H grade has a higher carbon content of up to 0.1% while 304L has a lower amount of carbon at around 0.03%. As higher carbon content improves the strength of stainless steel, 304H is widely used in high-temperature applications. 304L, with its lower carbon content, displays increased ductility and so is often used for welding components. 

Austenitic stainless steels like 304 have a yield strength that represents a comparatively low proportion of its tensile strength: between 40% and 45%. Its yield strength can be further improved when the material is cold-worked. This is particularly useful when making things like spring wire.  

Salient qualites of 304 grade stainless steel include:

  • Good corrosion resistance
  • No magnetism when the metal is annealed
  • An ability to be work-hardened
  • Exceptional ductility and weldability
  • High level of hygiene
  • Ease of cleaning
  • Good performance at both high and low temperatures

For more information about the many different types and grades of stainless steel, please visit the dedicated page on the BS Stainless website, where you will also find full details about all of the numerous different products we supply

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