There are several families of stainless steel with different physical properties. According to the American Iron and Steel Institute, stainless steel can be numerical and represented, such as 200 series, 300 series, 400 series. Both 201 and 304 are commonly used steel that has good corrosion resistance properties and good machining. and polishing performance. As we all know, they can be considered as substitutes for each other in some applications. So what is the difference?
Different chemical compositions
Chemical composition is the key to study and determine the physical properties of 201 and 304. We indicate the chemical composition of the two analyzed SS grades we are looking at in the following table.
| Grade | carbon (C) | silicon (Si) | manganese (Mn) | phosphorus (P) | sulfur (S) | chromium (Cr) | nickel (Ni) |
| AISI (304) | ≤0.08 | ≤1.00 | ≤2.00 | ≤0.045 | ≤0.03 | 18-20 | 8-10 |
| AISI (201) | ≤0.15 | ≤1.00 | 5.5-7.5 | ≤0.05 | ≤0.03 | 13.5-15.0 | 3.5-5.5 |
Different price
304 is more expensive than 201 due to nickel, which also leads to better corrosion resistance than 201.
Different appearance
304 tubes and sheets offer better brightness and are not easily oxidized. 201 contains more high manganese content with a dark light surface, easy to rust.
Different hardness
201 stainless steel material is relatively more rigid than 304 stainless steel, which is tougher, fatigue resistance is much better than 201.
Different applications
201 steel can be used as a substitute material for 304 steel because of its economy. It has magnetic processing after the cold. And it is used in railway vehicle quality or building decoration with less strict requirements. 304 is the most widely used heat-resistant steel, mainly used in food production equipment, chemical equipment, nuclear power, etc.
How to differentiate between 201 and 304?
Spark identification method. The amount, shape, bifurcation, and color of sparks generated by the oxidation of various elementary particles in iron and steel grinding conditions with high friction and high temperature will be different due to different types of steel. This method is used to identify the chemical composition (constituent elements) and the approximate content of the materials. Use grinding machine with grinding wheel to gently polish 201 and 304 stainless steel, 201 Stainless steel longer, thicker, more, and the rear fork, while 304 Stainless steel Spark steel shorter, thinner, less, and the rear fork. Pay attention to grinding to ensure that the test method is consistent to facilitate the distinction.
Identification of the stainless steel test solution. Also known as stainless steel pickling potion, this chemical reaction of the potion and stainless steel surface and produce different colors can determine the stainless steel coating model of stainless steel. Apply stainless steel pickling cream to 201 and 304 kinds of stainless steel pipes, respectively, and observe the color change of steel pipes after 2 minutes. The red color is 201 material, and light green or colorless is 304 material.
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Conclusion
When choosing stainless steel for its corrosion resistance, it is crucial to select the suitable grade to meet the environment and application. If used to make a stainless steel sink, there is no doubt that the quality of 304 is better than that of 201.
