Grade 304 stainless steel is a T 300 Series Stainless Steel austenitic. It has a minimum of 18% chromium and 8% nickel, combined with a maximum of 0.08% carbon. The remainder of its composition is made up of carbon, manganese, silicon and very small amounts of phosphorous and sulfur. It is defined as a Chromium-Nickel austenitic alloy. Grade 304 is the standard “18/8” stainless that you will probably see in your pans and cookery tools. Additionally, the metal is pliable under both hot and cold working, though it responds better to cold working; it will only work harden under cold working. Extended exposure to temperatures between 800–1500°F can lead to embrittlement and should be carefully monitored.
Grade 304L is the low carbon version of 304, and although the two types share many of the same properties, it is the differences in carbon content that differentiates them. It does not require post-weld annealing to effectively maximize corrosion resistance and so is extensively used in heavy gauge components (over about 6mm). Grade 304H with its higher carbon content finds application at elevated temperatures. Additionally, it also possesses a higher work hardening rate. 304L exhibits excellent resistance in a variety of atmospheres and temperatures, along with the corrosion and oxidation that occurs over time. However, like many stainless steels, it is susceptible to warm chlorine environments and can potential pit and crack.
Stainless Steels 304 and 304L can be commonly found dually certified. This utilized the widely applicable properties of both metals and meets the individual specifications for each.Grade 304/304L is the most widely used commercial grade of stainless steel supplied into numerous industry sectors. It has excellent corrosion resistance in ordinary atmospheric conditions, it is easily machined and is also easy to weld. Whilst performing well when exposed to relatively high temperatures, this grade of stainless steel like most austenitic stainless grades, also maintains its strength and toughness at sub-zero temperatures, making this an excellent choice for various applications and industries such as food & drink processing, petrochemical and construction.