What is the difference between SUS304 and SUS430?

The primary difference between SUS304 and SUS430 lies in their chemical composition, mechanical properties, corrosion resistance, and typical applications, as they belong to different stainless steel families.  

1. Chemical Composition:  
- SUS304: An austenitic stainless steel containing 18-20% chromium and 8-10.5% nickel, with a small amount of carbon. The nickel content enhances corrosion resistance and toughness.  
- SUS430: A ferritic stainless steel with 16-18% chromium and no nickel. The absence of nickel makes it more economical but reduces corrosion resistance and toughness.

2. Corrosion Resistance:  
- SUS304: Offers superior corrosion resistance, especially against rust and oxidation in acidic and saline environments, due to its nickel content. It is suitable for both indoor and outdoor use.  
- SUS430: Has moderate corrosion resistance, sufficient for indoor applications and dry environments. However, it is prone to rusting in aggressive or marine environments due to the lack of nickel.

3. Mechanical Properties:  
- SUS304: High strength and excellent ductility. It can be easily welded, formed, and processed for various applications.  
- SUS430: Lower strength and limited ductility compared to SUS304. It has less flexibility during forming and welding.

4. Magnetic Properties:  
- SUS304: Non-magnetic due to its austenitic structure.  
- SUS430: Magnetic because it has a ferritic crystal structure.

5. Applications:  
- SUS304: Commonly used in environments requiring high corrosion resistance, such as kitchen equipment, medical devices, chemical containers, and outdoor structures.  
- SUS430: Often used in less demanding applications like kitchen utensils, appliance trims, decorative panels, and automotive interior parts where cost-efficiency is important.

6. Cost:  
- SUS304: More expensive due to the addition of nickel.  
- SUS430: More cost-effective, making it suitable for budget-friendly applications.  

Summary:  
Choose SUS304 for high-corrosion environments, outdoor use, or applications needing superior durability and strength. Opt for SUS430 when cost is a priority, and the material will be used in less demanding, indoor conditions.