Many people believe that the higher the grade number of stainless steel, the better its performance. However, this is a misconception. The performance of stainless steel depends on its chemical composition and structure, not just the numerical grade. So why are there so many grades of stainless steel, and what do they represent? Let’s dive into the fascinating world of stainless steel to find out!
What is Stainless Steel?
Stainless steel is short for stainless and acid-resistant steel, referring to steel types that resist corrosion in weakly corrosive environments such as air, steam, and water or have specific stainless properties. To qualify as stainless steel, it must contain at least 10.5% chromium and have a carbon content no higher than 1.2%.
While all stainless steel offers resistance to corrosion, its ability to withstand chemical corrosion from acids, alkalis, or salts varies depending on its composition. Stainless steel primarily focuses on its resistance to environmental corrosion, while acid-resistant steel is specially designed to combat chemical corrosion.
Stainless Steel Grades
Stainless steel grades serve as its “identity card,” providing insight into its chemical composition, structure, and physical and chemical properties. There are several standard systems for grading stainless steel, including those used in China, the United States, Japan, and Europe. The most widely recognized system is the American AISI (American Iron and Steel Institute) designation.
AISI Grades
The AISI system uses a three-digit numbering format:
- The first digitrepresents the category:
- 2: Cr-Ni-Mn series
- 3: Cr-Ni series
- 4: Cr series
- 5: Low Cr series
- 6: Precipitation-hardening series
Examples: 201, 304, 403, 504
UNS System
The UNS (Unified Numbering System) combines a prefix letter with five digits, with the prefix “S” indicating stainless steel. The first digit represents the category, aligning closely with the AISI system, while the last two digits often denote unique composition or carbon content.
Examples: S20100, S30400, S30403, S30451
GB/T Standards
In China, the GB/T 24511-2017 standard provides a comprehensive comparison of stainless steel grades across various systems, ensuring compatibility and understanding for different applications.
Key Considerations in Choosing Stainless Steel
Each stainless steel grade is tailored for specific applications based on its properties and chemical composition. Selecting the right grade depends on the environment and usage requirements rather than simply opting for a higher numerical grade.
Applications in Vich Products
At Vich, we utilize premium grades of stainless steel for our products to meet diverse environmental and performance demands:
- Stainless Steel Cable Trays
- Constructed from 304, 316, and 316Lstainless steel for superior corrosion resistance and durability.
- Stainless Steel Safety Fences
- Components such as posts, mesh panels, and fixing rings are made from 304 stainless steelwith optional powder coating or electro-polishing for added protection and aesthetics.
Due to its high chromium content (usually at least 11%), stainless steel forms a natural chromium-rich oxide film on its surface, providing exceptional corrosion resistance. These features make our stainless steel products ideal for outdoor use, food and beverage industries, and high-humidity, highly corrosive environments.
The world of stainless steel is as versatile as its applications. Understanding the grades and their specific properties ensures that you choose the most suitable material for your needs. At Vich, we are committed to offering high-quality stainless steel safety solutions that stand the test of time in even the harshest environments.
