In the big family of stainless steel, 201 stainless steel and 304 stainless steel are both “star members”, and they are widely used in life and industry. These two types of stainless steel may look somewhat similar, but in fact they have many differences in composition, performance, and use. Understanding these differences can help us choose the right stainless steel material in various scenarios. Let’s take a deeper look.
What is 201 Stainless Steel?
201 stainless steel is a type of austenitic stainless steel, which was born in the 1930s. At that time, it came into being in order to find a stainless steel material with lower cost. It is mainly composed of chromium, nickel, manganese and other elements. The chromium content is generally between 16% and 18%, the nickel content is relatively low, at 3.5% to 5.5%, and the manganese content is 5.5% to 7.5%. The addition of manganese not only reduces the cost, but also enhances its strength and processing performance, making it easier to shape.
201 stainless steel has a good cost performance. Although its corrosion resistance is not as good as some high-end stainless steels, it still has a certain ability to resist atmospheric corrosion. It can play a good role in some scenes where corrosion resistance is not particularly high. For example, some indoor decorative structures, ordinary industrial equipment shells, etc. At the same time, its good processing performance allows it to be easily made into various shapes and sizes. It can be seen in kitchenware, auto parts and some architectural decoration fields.
What is 304 Stainless Steel?
304 stainless steel, also known as “18-8” stainless steel, is named because it contains about 18% chromium and 8% nickel. It is the most popular type of austenitic stainless steel and is a very versatile stainless steel material.
304 stainless steel has excellent corrosion resistance and can maintain good performance in a variety of environments. In an atmospheric environment, it can remain rust-free for a long time. It also has good tolerance to many chemicals and food and beverages. Moreover, it has good processing performance and excellent plasticity in the annealed state, which is suitable for various complex processing processes.
For some products that require multiple stretch forming, the use of high-nickel version of 304 stainless steel can achieve better forming effects. In addition, in some spring application scenarios that require strength, 304 stainless steel that has been cold-processed can meet the needs. It is worth mentioning that 304 stainless steel in the annealed state is non-magnetic, but it may be slightly magnetic after cold processing. Due to its excellent performance in all aspects, it is also considered food-grade stainless steel and is widely used in food processing equipment, kitchen utensils, and architectural decoration.
Key Differences Between 201 and 304 Stainless Steel
Chemical composition
From the perspective of chemical composition, there are obvious differences between 201 stainless steel and 304 stainless steel. The carbon content of 201 stainless steel is relatively high, up to 0.15%. The cabon content of 304 stainless steel is controlled at 0.07%.
In terms of alloying elements, the chromium content of 201 stainless steel is 16.0-18.0%, the nickel content is 3.5-5.5%, and the manganese content is 5.5-7.5%. The chromium content of 304 stainless steel is 17.5-19.5%, the nickel content is 8.0-10.5%, and the manganese content is only 2.00%. The difference in nickel and chromium content has an important impact on their performance. The higher nickel-chromium content of 304 stainless steel makes it more corrosion-resistant.
Corrosion resistance
Corrosion resistance is one of the important differences between the two. Since 304 stainless steel contains higher nickel and chromium, its corrosion resistance is significantly better than 201 stainless steel. In the same corrosive environment, 201 stainless steel is more likely to rust and corrode. For example, in an environment with high chloride ion content such as the seaside, 201 stainless steel may quickly rust, while 304 stainless steel can maintain its gloss and performance for longer.
Price
In terms of price, 201 stainless steel is usually cheaper than 304 stainless steel. This is mainly because 201 stainless steel has a lower nickel content, which is a relatively expensive metal element. Therefore, in some projects with strict cost control, if the corrosion resistance requirements are not particularly high, 201 stainless steel will be a more economical choice.
How to Distinguish Between 201 and 304 Stainless Steel?
Chemical analysis
Chemical analysis is a precise way to distinguish between the two. A portable X-ray fluorescence (XRF) analyzer can be used. It can accurately detect the specific content of elements such as nickel, chromium, and manganese in stainless steel, so as to determine whether it is 201 stainless steel or 304 stainless steel.
In addition, chemical spot tests can also be used to react with the nickel in stainless steel using specific chemical reagents, and the reaction results can be used to distinguish. Since 304 stainless steel has a higher nickel content, its reaction phenomenon will be different from that of 201 stainless steel.
Magnetic test
In the annealed state, 201 stainless steel and 304 stainless steel are usually non-magnetic or only weakly magnetic. However, after cold working, 201 stainless steel may show more obvious magnetism due to its higher manganese content. 304 stainless steel generally remains weakly magnetic or basically non-magnetic. Therefore, a simple test with a small magnet can also help us preliminarily determine the type of stainless steel.
Observe the appearance
From the appearance, 201 stainless steel may be slightly darker due to its lower chromium content and higher manganese content. 304 stainless steel is relatively brighter and whiter. However, this difference is subtle and it is not always reliable to observe it with the naked eye alone. Moreover, if both stainless steels have been surface treated, it is even more difficult to distinguish them by color.
Heat resistance test
In terms of heat resistance, 304 stainless steel performs better than 201 stainless steel. The two stainless steel samples can be tested in a high temperature environment to observe their oxidation. 304 stainless steel has stronger oxidation resistance at high temperatures, and the degree of surface oxidation will be much lighter than 201 stainless steel.
Choosing the Right Stainless Steel for Your Application
To choose the right stainless steel, you need to consider many factors comprehensively.
If the use environment has high requirements for corrosion resistance. For example, in environments such as the seaside and chemical production, 304 stainless steel clad plate is undoubtedly a better choice. It can maintain good performance for a long time in these harsh environments, reducing equipment maintenance and replacement costs. Like food processing equipment, kitchen utensils, etc. In order to ensure food safety, 304 stainless steel composite panel, a food-grade material, is also the best choice.
If cost is the primary consideration. And the use environment is relatively mild. The requirements for corrosion resistance are not particularly strict, 201 stainless steel composite plate is more suitable. For example, indoor decorative structures and some ordinary industrial products that are sensitive to cost. 201 stainless steel sheet can meet basic needs and control costs.
Conclusion
Although both 201 stainless steel and 304 stainless steel belong to the stainless steel family, they have obvious differences in composition, performance, price, etc. 201 stainless steel has low cost and high strength, and is suitable for use in cost-sensitive and less corrosive environments. 304 stainless steel, with its excellent corrosion resistance, good processing performance and food-grade safety characteristics, plays an important role in fields with high corrosion resistance and hygiene requirements.
Through chemical analysis, magnetic testing, appearance observation, price judgment, mechanical property testing and heat resistance testing, we can distinguish these two types of stainless steel more accurately. In practical applications, as long as the specific use environment, cost budget and processing requirements are comprehensively considered, the most suitable stainless steel material can be selected to maximize their value in their respective fields.
