What is the difference between SUS304 and SUS304H stainless steel?

Stainless steel is a common metal material, which is widely used in various fields. Among them, SUS304, SUS304H and SUS304L are common stainless steel materials, which have some differences in chemical composition and application.

Difference in chemical composition
SUS304H stainless steel is a high-carbon version of stainless steel 304, with a higher carbon content, usually between 0.04% and 0.1%. The high carbon content gives 304H better high-temperature strength and corrosion resistance, and is suitable for applications in high-temperature environments, such as stoves, burners, and high-temperature pipelines.
SUS stainless steel 304L is a low-carbon version of stainless steel 304, with a carbon content controlled below 0.03%. The low carbon content helps to improve the intergranular corrosion resistance of 304L, making it suitable for welded structures and applications in some special environments, such as the chemical industry and medical equipment.

Difference in corrosion resistance
Due to the addition of high carbon content, stainless steel 304H plate has better corrosion resistance in high-temperature environments, and can resist erosion by acidic gases and high-temperature corrosive media.
Stainless steel 304L alloy plate improves its intergranular corrosion resistance by reducing the carbon content, and has better corrosion resistance for corrosive media in some special environments, such as acidic chloride solutions and seawater.

Difference in welding performance
Due to the presence of high carbon content, stainless steel 304H cold-rolled plate needs to be preheated and the welding temperature controlled during welding to prevent the occurrence of intergranular corrosion.
Due to the characteristics of low carbon content, the welding performance of stainless steel 304L hot-rolled plate is better than 304 and 304H, which is more suitable for the application of welded structures and has a lower risk of intergranular corrosion after welding.

Due to the presence of high carbon content, stainless steel 304H has better oxidation resistance and high temperature strength in high temperature environment. In contrast, the performance of 304 and 304L in high temperature environment is slightly reduced.

Difference in application field
Stainless steel 304H is often used in the manufacture of equipment and components in high temperature environment, such as high temperature furnaces, burners, petrochemical equipment, etc.
Stainless steel 304L is suitable for occasions requiring intergranular corrosion resistance, such as chemical industry, pharmaceutical equipment, marine environment, etc.

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