Stainless steel is a metal material widely used in various industrial fields and is favored for its excellent corrosion resistance and mechanical properties. Among them, 304 and 904L stainless steel are two common models, and they differ significantly in many aspects.

Chemical composition  

● 304 stainless steel
304 stainless steel, also known as 18/8 stainless steel, is so named because it contains at least 18% chromium (Cr) and 8% nickel (Ni). The main chemical components of this stainless steel also include small amounts of carbon (C), silicon (Si), manganese (Mn), phosphorus (P) and sulfur (S). According to the American ASTM standard, the national brand number of 304 stainless steel is 06Cr19Ni10, which belongs to the austenitic stainless steel category.

● 904L stainless steel
904L stainless steel is a super austenitic stainless steel, also known as N08904 or 1.4539. Its chemical composition contains a high proportion of chromium (Cr), nickel (Ni) and molybdenum (Mo), as well as a certain amount of copper (Cu). Specifically, the chromium content of 904L stainless steel is between 19.0% and 23.0%, the nickel content is between 23.0% and 28.0%, the molybdenum content is between 4.00% and 5.00%, and the copper content is between 1.00% and 2.00% . The presence of these high alloying elements gives 904L stainless steel excellent corrosion resistance.

Performance characteristics

● 304 stainless steel
304 stainless steel has good comprehensive properties, including excellent corrosion resistance and toughness. It can resist corrosion in a variety of environments, such as atmosphere, water and some weak acid and weak alkali media. In addition, 304 stainless steel also has good processing performance and toughness, and is widely used in the industrial and furniture decoration industries, as well as the food and medical industries. However, it should be noted that although 304 stainless steel has good corrosion resistance, its corrosion resistance may decrease under certain specific media or high temperature conditions.

● 904L stainless steel
904L stainless steel is known for its excellent corrosion resistance and high strength. It can show excellent corrosion resistance in a variety of corrosive media, and is especially suitable for processing highly corrosive media such as sulfuric acid, acetic acid, formic acid and phosphoric acid. In addition, 904L stainless steel also has good processing and welding properties and can be formed and processed through conventional metal processing processes. Due to its high alloy content, 904L stainless steel has higher hardness and good wear resistance after quenching, making it suitable for applications requiring high wear resistance.

Application areas

● 304 stainless steel
304 stainless steel is widely used in many fields due to its wide applicability and good comprehensive performance. In the food and medical industry, it is used to make equipment that comes into contact with food and is favored for its corrosion resistance and hygienic properties. In the industrial and furniture decoration industries, 304 stainless steel is used to make equipment and parts that require good corrosion resistance and formability. In addition, it is also used in construction, chemical industry, petroleum and other fields.

● 904L stainless steel
904L stainless steel is mainly used in chemical industry, petroleum, marine engineering and other fields because of its extremely strong corrosion resistance and high temperature resistance. In the chemical industry, it is used to manufacture equipment that handles corrosive media such as sulfuric acid and acetic acid. In marine engineering, due to its excellent seawater corrosion resistance, it is suitable for ships, offshore platforms, etc. In addition, 904L stainless steel is also used in pulp and paper equipment in the paper industry, as well as flue gas desulfurization devices in environmental protection equipment.

Price and Cost

Because 904L stainless steel contains a higher proportion of alloying elements and has better properties, its price is usually higher than 304 stainless steel. When selecting stainless steel materials, in addition to considering its performance characteristics and application fields, you also need to consider cost factors.

Conclusion

There are significant differences between 304 and 904L stainless steel in terms of chemical composition, performance characteristics, and application fields. The choice of stainless steel depends on the specific application, performance needs and budget. If you need higher corrosion resistance and high temperature resistance, 904L stainless steel is a better choice; if you have stricter cost control and the application scenario does not have particularly high performance requirements, 304 stainless steel is a more cost-effective option. choice.