304 stainless steel is the most widely used austenitic steel. Sometimes called 18/8 stainless steel because it contains 18% chromium and 8% nickel. Grade 304 offers excellent chemical, oxidation and corrosion resistance over a wide temperature range. However, it is susceptible to pitting corrosion and stress corrosion cracking when exposed to chlorides.
In addition to its excellent corrosion resistance, 304 stainless steel is also highly ductile. Therefore, they can be easily shaped and processed into a variety of products. The formability of 304 stainless steel is higher than that of 316 grade. However, they require annealing after cold working to minimize work hardening.
304 is easy to form and weld, and is easily roll-formed into a variety of components for use in industry, construction and transportation. Because it can be heavily drawn, this grade of stainless steel is the material of choice for drawn stainless steel parts such as sinks, hollowware, and pans.
304 stainless steel is also used in mechanical fasteners (nuts, bolts and screws), industrial factory equipment (pressure vessels, storage vessels, pipes), kitchen utensils, tableware, cookware, decorative parts and building paneling, etc.
304 grades are available in low carbon and high carbon content variants, namely 304L grade and 304H grade.
304L stainless steel has the following three major characteristics:
Low carbon content: The carbon content of 304L grade is lower than standard 304 grade. Carbon content is usually limited to a maximum of 0.03%, thereby minimizing the risk of sensitization and the formation of chromium carbides at grain boundaries.
Improved weldability: Due to its low carbon content, 304L improves weldability. This makes it suitable for welding applications without the need for post-weld annealing to restore corrosion resistance.
Reduced Sensitization: The lower carbon content in 304L reduces the potential for sensitization, a phenomenon in which chromium carbides form at grain boundaries, resulting in reduced corrosion resistance.
Because of these properties, 304L is commonly used in applications requiring welding, such as welded components in the chemical, petrochemical, and food processing industries.
Compared with the standard 304 grade, 304H has a higher carbon content. Carbon content is usually in the range of 0.04-0.1%. Higher carbon content improves the alloy's creep strength and high-temperature strength properties. Therefore, 304H is typically used in applications requiring high temperature strength, such as industrial furnaces, heat exchangers, and high temperature chemical processing.