Stainless steel is one of the most commonly used materials across industries due to its excellent corrosion resistance, durability, and versatility. Among its many grades, 304L and 304H stand out as two variants of the popular 304 stainless steel, each engineered for different performance requirements. Although they share a similar chemical composition, the key difference lies in their carbon content, which significantly affects their mechanical properties and suitability for specific environments.
In this article, we’ll break down what 304L and 304H stainless steel are, explore their main differences, compare their applications, and help you understand which one is best suited for your project.
What Is 304L And 304H Stainless Steel
304L stainless steel is a low-carbon version of 304 stainless steel, with a carbon content of up to 0.03%, while standard 304 stainless steel has a carbon content of 0.08%. With this lower carbon content, the risk of carbide precipitation during welding is minimized, which enhances its resistance to intergranular corrosion. This makes 304L very suitable for applications that require a lot of welding, such as the chemical and petrochemical industries.
In contrast, 304H stainless steel has a relatively higher carbon content, up to 0.10%. The increased carbon content makes it stronger in high-temperature environments, so it is suitable for high-temperature applications, commonly found in industrial boilers, heat exchangers and piping systems.
Key Differences Of 304L And 304H Stainless Steel
The two main grades of 304 stainless steel are low-carbon 304L and high-carbon 304H. 304L has a carbon content of up to 0.03%, while 304H has a carbon content between 0.04% and 0.1%, which gives it better strength at high temperatures.
Generally speaking, 304 stainless steel is not suitable for use at very high temperatures. However, it is resistant to oxidation at temperatures up to 925°C for continuous use and 870°C for intermittent use. When used at temperatures above 425°C, it may experience carbide precipitation and inter-corner corrosion.
304L is less prone to carbide precipitation at higher temperatures due to its lower carbon content. 304H is significantly stronger at high temperatures, so it is often chosen when both high temperature resistance and corrosion resistance are required, such as in flue gas chimneys, where gases condense to form corrosive acidic liquids. 304H is often used for this purpose.
Applications And Uses Of 304L And 304H Stainless Steel
304H stainless steel composite sheet is widely used in the food industry due to its corrosion resistance and is also a preferred material in the dairy industry. It is also commonly used in high-quality tableware and is called 18/8 based on the percentage of chromium and nickel. It is also often made into sinks, dishwashing basins and other kitchen utensils. Its easy processing and forming characteristics make it suitable for the production of pots and pans.
304H is also often used in fresh water supply because its hard oxide layer can inhibit the growth of bacteria that may affect fresh water. Compared with other materials, it is relatively low in cost, so it has many applications in the construction field. Its heat resistance makes it excellent in heat exchangers, and it will not crack or corrode in the temperature range of 500°C to 800°C. And it has strong tolerance to extreme thermal environments and is a low-maintenance material for those difficult-to-reach applications.
How to Choose Between 304L and 304H for Your Project
When selecting between 304L and 304H stainless steel for your project, it’s essential to consider both the operating environment and fabrication requirements. While both are derived from the same base grade (304), their differing carbon content makes them suitable for different industrial conditions.
304L stainless steel is ideal for applications that require extensive welding or exposure to corrosive environments at lower temperatures. Its low carbon content minimizes the risk of intergranular corrosion, making it an excellent choice for chemical storage tanks, pressure vessels, and stainless steel composite plates that are assembled using welding processes. Projects involving food processing equipment or pharmaceutical storage also often prefer 304L due to its superior corrosion resistance and hygiene performance.
On the other hand, 304H stainless steel is better suited for high-temperature environments where increased strength and structural integrity are required. Its higher carbon content gives it improved creep resistance, which is essential in boilers, heat exchangers, and superheated steam piping systems. It is also frequently used in stainless steel plates for elevated temperature service in petrochemical plants, power generation facilities, and industrial furnaces.
In short, choose 304L for better weldability and corrosion resistance in low- to mid-temperature conditions, and opt for 304H when dealing with high-temperature, high-stress engineering projects where long-term mechanical strength is critical.
Other Variants Of 304 Stainless Steel
In addition to 304, 304L, and 304H, there are several other variations of 304 stainless steel, each with unique properties for specific applications.
304N stainless steel has nitrogen added to increase strength while maintaining good corrosion resistance. The addition of nitrogen also improves its mechanical properties, making it suitable for structural applications where strength is required.
304F stainless steel is designed for improved machinability. The addition of sulfur improves its machinability without significantly affecting corrosion resistance, and is often used in high-speed machining applications such as fasteners and accessories.
304D stainless steel, while less common, is designed for special applications that require a balance of strength and corrosion resistance, and is often used in decorative and architectural components.
Conclusion
Both 304L and 304H stainless steels offer excellent corrosion resistance and share many similarities, but their carbon content creates a clear divide in performance under specific conditions. 304L excels in applications that require extensive welding and corrosion resistance at low to moderate temperatures, while 304H is the ideal choice for high-temperature structural applications due to its enhanced strength.
Understanding their differences will help you make informed decisions in material selection for your industrial, structural, or commercial needs. Whether you prioritize weldability or high-temperature strength, selecting the right grade of stainless steel can ensure both long-term performance and cost efficiency.
