Stainless steel is one of the most common materials for sheet metal fabrication services and various types of stainless steel grades can be formed into metal sheets and applied for different uses. Speaking of 304 and 201 stainless steel sheets, what’s the difference and how to distinguish them?
1. Price: the commonly used stainless steel sheets are divided into different grades, including SS201 and SS304. They have different compositions. Usually, 304 stainless steel sheets are more expensive than 201 sheets. 201 stainless steel is often regarded as a substitute for 304.
2. Application: 201 is alternative steel to 301 steel. It is magnetic after cold processing and is used for railway vehicles. 304 is the most widely used stainless steel and heat-resistant steel. Used for food production equipment, general chemical equipment, nuclear energy, etc.
3. Composition: 201 sheet has high manganese content, bright surface with dark brightness, high manganese content, and easy to rust. 304 contains more chromium, the surface is matte and does not rust. Another main difference between 201 and 304 is the content of nickel.
4. Corrosion resistance: The most important thing is that the corrosion resistance is different. The corrosion resistance of the 201 metal sheets is very poor, so the price is much cheaper. Because 201 has low nickel content, the price is lower than that of 304, so the corrosion resistance is not as good as that of 304. The content of alloying elements, generally speaking, when the content of chromium is 10.5%, steel is not easy to rust. The higher the content of chromium and nickel, the better the corrosion resistance. For example, the nickel content of 304 material is 8-10%, and the chromium content reaches 18-20%. Such stainless steel will not rust under normal circumstances.
5. Mechanical properties: 201 stainless steel has high hardness, but its toughness is not as good as 304. 304 has better fatigue resistance.
6. Color: 201 has high manganese content, bright surface with dark brightness, high manganese content, and is easy to rust. 304 contains more chromium, the surface is matte and does not rust.
7. Others: Stainless steel is not easy to rust because chromium-rich oxide is formed on the surface of the steel body, which can protect the steel body. Sheet metal 201 is high manganese stainless steel, with higher hardness than 304, high carbon, and low nickel.
How to distinguish 304 and 201 for stainless steel sheet metal fabrication? 304 stainless steel sheet is often used in the inner layer such as in direct contact with water) because of its excellent corrosion resistance. 201 stainless steel sheet is often used in the outer layer of an insulated water tank because of its poor corrosion resistance. However, 201 is cheaper than 304, which is often used by some bad businesses as 304. The service life of stainless steel water tanks made of 201 stainless steel is very short, and they are often corroded by water in 1-2 years, leaving potential safety hazards to users.
Here’s a simple way to identify these two materials in sheet metal fabrication:
1. 304 and 201 stainless steel are used in stainless steel water tanks, and the surface is usually matte. So we identify it by the naked eye and hand touch. 304 stainless steel has good luster and brightness, and is very smooth when you touch it; 201 stainless steel feels rough, but the color is not shiny. In addition, wet your hand with water and touch two kinds of stainless steel sheets respectively. After touching, the water stain fingerprint on the 304 sheets is easier to erase, but 201 is not easy to erase.
2. Install the grinding wheel with the grinder and gently grind the two types of metal sheets. During grinding, the sparks of stainless steel sheet 201 are relatively long, thick, and more, while the sparks of sheet 304 are relatively short, thin, and less. The grinding force must be light, and the two grinding forces are consistent, which is convenient to distinguish.
3. Apply stainless steel pickling paste on two kinds of stainless steel sheets respectively. After 2 minutes, look at the color change of stainless steel at the coating. The color is 201 for blackening and 304 for whitening or no discoloration.