Questions about 201 and 304 medical stainless steels

201 stainless steel should not be used as tableware, food containers, the so-called 201 on the market is a lot of 200 materials, most of them are produced by some small steel mills, and the chemical composition is uncertain. The stainless steel material that comes into contact with food is also the most basic 304 material. There are special 304 material food-grade stainless steel plates and pipes, and it is more safe to choose these materials.

Among the unqualified stainless steel materials, many harmful metals exceed the standard, and they are easy to dissolve at high temperatures, causing harm to the body, the most common of which is manganese metal exceeding the standard. Some time ago, there was also a problem of excessive manganese in a domestic famous brand stainless steel pot.

The problem of high temperature, 201 and other stainless steel unqualified stainless steel materials, even if they are made into water cups, there will be problems when they are filled with boiling water. This has also been experimented with. The stainless steel material of 304 can withstand a temperature of about 700 degrees. It should be enough for us to use in our lives.

The reason why stainless steel can prevent rust is because of the amount of chromium and nickel contained in it.

The difference between 201 stainless steel and 304 stainless steel is mainly due to the different content of chromium (Cr) and nickel (Ni).

For example, standard 304 stainless steel, which contains 18% chromium and 9% nickel.

201 stainless steel contains 15% chromium and 5% nickel, so the anti-rust performance is much different.

201 material is relatively hard and easy to crack, so it should be considered during use.

304 is generally used in food machinery, and these two kinds of stainless steel are not resistant to acid and alkali.

In terms of medical treatment, generally neither material is used. Medical treatment generally chooses 316 or 316L or above stainless steel that is better than their grade. In service, the corrosion resistance of 304 or 201 is inferior to that of 316.

According to the composition, it can be divided into CR series (400 series), Cr Ni series (300 series), Cr Mn Ni (200 series) and precipitation hardening (600 series).

200 series - chromium-nickel-manganese austenitic stainless steel.

300 Series – Chromium-nickel austenitic stainless steel.

301—Good ductility, used for molding products. It can also be quickly hardened by machining. Good weldability. The wear resistance and fatigue strength of Yuanyun are better than those of 304 stainless steel.

302-The corrosion resistance is the same as 304, and the strength is better because the carbon content is relatively high.

303—By adding a small amount of sulfur and phosphorus, it is easier to cut than 304.

304 — i.e. 18-8 stainless steel. The GB grade is 0Cr18Ni9.

309—Better temperature resistance than 304.

316-After 304, the second most widely used steel grade, mainly used in the food industry, pharmaceutical industry and surgical equipment, the addition of molybdenum element to obtain a special corrosion-resistant structure. Because it has better resistance to chloride corrosion than 304, it is also used as "marine steel". SS316 is commonly used in nuclear fuel** installations.

18 grade 10 stainless steel is also generally suitable for this application class. [1] Stainless steel bucket model 321 – similar to 304 except for the addition of titanium to reduce the risk of corrosion in the welds of the material.

400 Series – Ferritic and martensitic stainless steels.

408—good heat resistance, weak corrosion resistance, 11% CR, 8% NI.

409—the cheapest model (Anglo-American), usually used as a car exhaust pipe, is ferritic stainless steel (chrome steel).

410-martensitic (high-strength chromium steel), good wear resistance, poor corrosion resistance.

416—Sulfur is added to improve the processability of the material.

420—"Cutting tool grade" martensitic steel, similar to Brinell high-chromium steel, the earliest stainless steel. It is also used for surgical knives and can be made very bright.

430 – Ferritic stainless steel, for decoration, e.g. for automotive accessories. Good formability, but poor temperature resistance and corrosion resistance.

440—High-strength cutting edge steel, slightly higher carbon content, after proper heat treatment, can obtain high yield strength, hardness can reach 58HRC, belongs to the hardest stainless steel. The most common example of application is the "Sakura Crack Kei razor blade". There are three commonly used models:

440A, 440B, 440C, and 440F (easy to process).

500 Series – Heat-resistant chromium alloy steel.

600 Series – Martensitic precipitation hardening stainless steel.

Stainless steel 630 - the most commonly used precipitation hardening stainless steel model, usually also called 17-4; 17%cr，4%ni。

The differences between 201 and 304 are: different compositions, different corrosion resistance, and different aspects of the main application.

The composition is different: 201 stainless steel contains 15% chromium and 5% nickel. 201 stainless steel is an alternative to 301 steel. Standard 304 stainless steel, which contains 18% chromium and 9% nickel.

The corrosion resistance is different: 201 is higher in manganese, the surface is very bright with dark brightness, and the higher in manganese is easy to rust. 304 contains more chromium, and the surface is matte and not rusty.

Stainless steel is not easy to rust because the formation of chromium-rich oxides on the surface of the steel body can protect the steel body, 201 material belongs to high manganese stainless steel, which is harder than 304, high carbon and low nickel.

The main application aspects are different: 201 stainless steel, with a certain acid resistance, alkali resistance, high density, polishing without bubbles, no pinholes, etc., is the production of various cases, strap case back high-quality materials, etc. It is mainly used for decorative pipes, industrial pipes, and some shallow drawing products.

304 stainless steel has the characteristics of good processing performance and high toughness, and is widely used in industrial and furniture decoration industries and food and medical industries.

In contrast, 201 stainless steel has a dull surface color, and 304 stainless steel has a smooth and bright surface. The corrosion resistance, acid and alkali resistance and other properties of 201 stainless steel are not as good as 304 stainless steel. Since 201 stainless steel has a higher carbon content than 304 stainless steel, 201 stainless steel is more brittle and hard than 304 stainless steel.

For 304 stainless steel, the Ni element in its composition is very important, which directly determines the corrosion resistance and value of 304 stainless steel. The manganese content in 201 Buyoudan rust steel is high, and the manganese in it is easy to be precipitated when it is in contact with acidic substances. 201 stainless steel mainly covers construction, industrial and other scenarios, while 304 stainless steel has an absolute advantage in performance, so the coverage is wider and more comprehensive than 201 stainless steel.

In addition, the choice of stainless steel material is also one of the factors to consider. 304 stainless steel is better than 201 stainless steel because of its performance in all aspects, so 304 stainless steel ** is more expensive than 201 stainless steel.

Difference Between 304 Stainless Steel and 201 Stainless Steel:

1. Different chemical compositions: generally stainless steel is based on iron, carbon plus nickel, chromium, manganese and other metal elements to produce anti-rust performance, 304 stainless steel contains more nickel and chromium than 201 stainless steel, and manganese is less than 201 stainless steel.

2. Chemical properties: nickel-chromium metal mainly plays the role of anti-corrosion, 304 stainless steel contains more nickel-chromium, and the corrosion resistance is stronger than that of 201 stainless steel.

3. Physical properties: 304 stainless steel has strong toughness, 201 stainless steel has insufficient toughness, and the tensile process requires a lot of force and is easy to crack.

4. Safety performance: 201 stainless steel contains high manganese elements, which is harmful to the human nervous system, and 304 stainless steel is safe to be an edible grade material, and the current edible grade stainless steel is 304 stainless steel and above.

There are many types of stainless steel on the market, and the more common ones are 304 stainless steel and 201 stainless steel. So what are the differences between 304 and 201 stainless steel? The following is a brief introduction to you.

1. The content of ingredients is different.

The chemical composition content of 304 stainless steel and 201 stainless steel is different, for example, the carbon, manganese and nitrogen content of 201 stainless steel is higher than that of 304 stainless steel, and the content of chromium and nickel is lower than that of 304 stainless steel. The chemical composition of the two stainless steel contents is different, resulting in differences in product performance and other aspects. For example, 304 stainless steel is soft and has superior corrosion resistance.

The 201 stainless steel material is relatively hard and prone to rust.

2. The place of use is different.

The difference in the performance of 201 stainless steel and 304 stainless steel determines that the place where the product is used will be different. For example, 304 stainless steel is suitable for use in wet occasions such as bathrooms. 201 stainless steel is more suitable for indoor drying.

If compared from the appearance of the product, the color of 201 stainless steel is dark, and the feel is rough. And 304 stainless steel has a good luster and a smooth feel.

3. The two are different.

The ** of 201 stainless steel is lower than the ** of 304 stainless steel, and some merchants use 201 stainless steel to use 304 stainless steel fraudulently for profit. When you buy stainless steel, you can apply stainless steel pickling paste to stainless steel, about a few minutes later, if the color of the stainless steel coating is black, the product is 201 stainless steel.

If the color does not change or is whitish, the product is 304 stainless steel. Or we can use a knife to scratch the stainless steel surface, and the 201 stainless steel surface will show obvious scratches. If it is made of stainless steel made of 304, the scratches on the surface are not obvious.

Summary: What is the difference between 304 and 201 stainless steel, I will briefly introduce it to you here. I hope that after reading this article, you can understand the difference between 304 stainless steel and 201 stainless steel.

Don't confuse these two stainless steel materials when buying stainless steel.