What is the difference between 347 and 304 stainless steel coils?

Hey there! As a supplier of stainless steel coils, I often get asked about the differences between various types of stainless steel. One common question is the difference between 347 and 304 stainless steel coils. So, let's dive right in and explore what sets these two types apart.

Chemical Composition

First off, the chemical composition of these two stainless steel coils is quite different. 304 stainless steel is one of the most widely used grades. It contains about 18 - 20% chromium and 8 - 10.5% nickel. This combination gives it good corrosion resistance and formability. On the other hand, 347 stainless steel has a similar base composition with 17 - 19% chromium and 9 - 13% nickel. But the key difference is that 347 contains columbium (niobium) and tantalum. These elements act as stabilizers, which prevent the formation of chromium carbide during welding and high - temperature applications.

This difference in composition means that they perform differently in various environments. For example, 304 is great for general - purpose applications like kitchen appliances, food processing equipment, and architectural trim. It can handle mild to moderate corrosion, but in more aggressive environments or at high temperatures, it might not be the best choice.

347, with its stabilizers, is more suitable for applications where the steel will be exposed to high temperatures for extended periods. It's commonly used in the chemical processing industry, heat exchangers, and furnace parts. The stabilizers in 347 help maintain its corrosion resistance even after being subjected to high - temperature stress.

Mechanical Properties

When it comes to mechanical properties, there are also some notable differences. 304 stainless steel has good ductility, which means it can be easily formed into different shapes. It has a tensile strength of around 515 MPa and a yield strength of about 205 MPa. This makes it a popular choice for applications where forming operations like bending, stamping, and deep - drawing are required.

347 stainless steel, while also having good ductility, has slightly higher strength properties. Its tensile strength is around 515 - 655 MPa, and the yield strength is about 205 - 310 MPa. This makes it more suitable for applications where higher strength is needed, especially in high - temperature environments. The higher strength of 347 helps it maintain its shape and integrity under stress at elevated temperatures.

Weldability

Weldability is another important factor to consider. 304 stainless steel is relatively easy to weld. It can be welded using common welding methods such as TIG (Tungsten Inert Gas) welding, MIG (Metal Inert Gas) welding, and stick welding. However, during welding, there is a risk of sensitization. Sensitization occurs when chromium carbide precipitates at the grain boundaries, which can reduce the corrosion resistance in the heat - affected zone.

347 stainless steel, thanks to the columbium and tantalum stabilizers, has better resistance to sensitization during welding. This means that after welding, it retains its corrosion resistance more effectively than 304. So, if your application involves a lot of welding, especially in high - temperature or corrosive environments, 347 might be the better option.

Cost

Cost is always a consideration in any project. Generally, 304 stainless steel is more cost - effective than 347. The additional alloying elements in 347, such as columbium and tantalum, make it more expensive to produce. So, if your project has a tight budget and doesn't require the special properties of 347, 304 is a more economical choice.

Applications

Let's talk a bit more about the specific applications of each type. As I mentioned earlier, 304 is everywhere. You can find it in your home kitchen, in the form of sinks, countertops, and cookware. It's also used in the automotive industry for trim and exhaust systems. In the construction industry, it's used for handrails, facades, and structural components.

347, on the other hand, is used in more specialized applications. In the chemical industry, it's used for pipes, tanks, and vessels that handle corrosive chemicals at high temperatures. It's also used in the power generation industry for boiler components and superheaters. The ability of 347 to maintain its properties at high temperatures makes it invaluable in these critical applications.

Other Related Stainless Steel Coils

If you're still exploring your options, we also offer other types of stainless steel coils. For example, 444 STAINLESS COIL is a ferritic stainless steel with excellent corrosion resistance in many environments, especially in areas where chloride - induced corrosion is a concern. It's often used in water treatment systems and automotive exhausts.

317L Stainless Steel Coil is an austenitic stainless steel with a higher molybdenum content than 304 and 347. This gives it even better corrosion resistance in harsh chemical environments. It's commonly used in the pharmaceutical and chemical processing industries.

SS310 SS410 Stainelss Steel Coil offers a range of properties depending on the specific grade. SS310 is known for its high - temperature resistance and is used in furnace parts and heat - treating equipment. SS410 is a martensitic stainless steel with good strength and wear resistance, often used in cutlery and machine parts.

Conclusion

In conclusion, the choice between 347 and 304 stainless steel coils depends on your specific application. If you need a cost - effective, general - purpose material with good formability and mild corrosion resistance, 304 is the way to go. But if you're dealing with high - temperature applications, welding, or more aggressive environments, 347 might be the better option.

As a stainless steel coil supplier, we have a wide range of products to meet your needs. Whether you're working on a small DIY project or a large - scale industrial application, we can help you find the right stainless steel coil. If you're interested in learning more or making a purchase, feel free to reach out to us for a quote and to discuss your requirements. We're here to help you make the best choice for your project.

References

• ASM Handbook Volume 13A: Corrosion: Fundamentals, Testing, and Protection
• "Stainless Steel: A Technical Guide" by The Nickel Institute