Newest Comparison Table of Stainless Steel Grades

Stainless steel is widely used in the global manufacturing industry, but due to the different standards and naming methods of stainless steel in various countries and regions, there are often some obstacles in understanding and communication. In order to help enterprises and buyers better identify and select suitable materials, JIEHUANG has compiled a detailed international comparison table of stainless steel grades. This table compares the main international standards (such as China's GB standard, the United States' ASTM standard, Europe's EN standard and Japan's JIS standard) for quick reference when selecting and purchasing stainless steel materials. This can not only effectively improve the efficiency of cross-border procurement, but also help ensure the accuracy and consistency of material selection.

RFQ:

1. What are the corrosion resistance of various stainless steels?

304 is a general-purpose stainless steel that is widely used to make equiPment and parts that require good comprehensive performance (corrosion resistance and formability). 301 stainless steel shows obvious work hardening when deformed and is used in various occasions that require higher strength.

302 stainless steel is essentially a variant of 304 stainless steel with a higher carbon content, which can be made to have higher strength through cold rolling.

302B is a stainless steel with a higher silicon content and has higher resistance to high-temperature oxidation. 303 and 303Se are free-cutting stainless steels containing sulfur and selenium respectively, which are used in occasions that mainly require free-cutting and high surface finish. 303Se stainless steel is also used to make parts that require hot upsetting because under such conditions, this stainless steel has good hot workability.

304L is a variant of 304 stainless steel with a lower carbon content and is used in occasions that require welding. The lower carbon content minimizes the precipitation of carbides in the heat-affected zone near the weld, and the precipitation of carbides may cause intergranular corrosion (weld erosion) of stainless steel in certain environments.

304N is a nitrogen-containing stainless steel, and nitrogen is added to increase the strength of the steel.

305 and 384 stainless steels contain higher nickel content and have lower work hardening rates, making them suitable for various occasions with high requirements for cold formability.

308 stainless steel is used to make welding rods.

309, 310, 314 and 330 stainless steels all have higher nickel and chromium contents in order to improve the oxidation resistance and creep strength of the steel at high temperatures. 30S5 and 310S are variants of 309 and 310 stainless steels, the only difference being that they have a lower carbon content in order to minimize the precipitation of carbides near the weld. 330 stainless steel has particularly high resistance to carburization and thermal shock.

316 and 317 stainless steels contain aluminum, so their pitting corrosion resistance in marine and chemical industrial environments is much better than that of 304 stainless steel. Among them, 316 stainless steel has variants including low-carbon stainless steel 316L, high-strength stainless steel 316N containing nitrogen, and free-cutting stainless steel 316F with a high sulfur content.

321, 347 and 348 are stainless steels stabilized with titanium, niobium, tantalum and niobium respectively, suitable for welding components used at high temperatures. 348 is a stainless steel suitable for the nuclear power industry, and has certain restrictions on the amount of tantalum and cobalt.

2. Why is stainless steel also magnetic?

Answer: People often think that magnets can attract stainless steel to verify its quality and authenticity. If it does not attract magnetism, it is considered to be good and genuine; if it attracts magnetism, it is considered to be a fake. In fact, this is an extremely one-sided, impractical and wrong identification method.

There are many types of stainless steel, which can be divided into several categories according to the organizational structure at room temperature:

1. Austenite: such as 304, 321, 316, 310, etc.;

2. Martensite or ferrite: such as 430, 420, 410, etc.;

Austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic.

Most of the stainless steel used for decorative tube sheets is austenitic 304 material, which is generally non-magnetic or weakly magnetic. However, due to fluctuations in chemical composition or different processing conditions caused by smelting, magnetism may also occur, but this cannot be considered as counterfeit or unqualified. What is the reason?

As mentioned above, austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic. Due to component segregation or improper heat treatment during smelting, a small amount of martensite or ferrite structure will be caused in austenitic 304 stainless steel. In this way, 304 stainless steel will have weak magnetism.

In addition, after cold working, the organizational structure of 304 stainless steel will also transform into martensite. The greater the cold working deformation, the more martensite transformation, and the greater the magnetism of the steel. For example, a batch of steel strips, when producing Φ76 tubes, there is no obvious magnetic induction, and when producing Φ9.5 tubes. The magnetic induction is more obvious due to the larger cold bending deformation. The deformation of square and rectangular tubes is larger than that of round tubes, especially the corners, and the deformation is more intense and the magnetism is more obvious.

To completely eliminate the magnetism of 304 steel caused by the above reasons, high-temperature solid solution treatment can be used to restore the stable austenite structure, thereby eliminating the magnetism.

It should be pointed out in particular that the magnetism of 304 stainless steel caused by the above reasons is completely different from the magnetism of other materials such as 430 and carbon steel, that is, the magnetism of 304 steel always shows weak magnetism.

This tells us that if stainless steel has weak magnetism or no magnetism at all, it should be judged as 3-4 or 316 material; if it is the same as the magnetism of carbon steel, it shows strong magnetism, so it is judged not to be 304 material.

We suggest that when buying stainless steel products, you should choose products from reputable manufacturers, don't be greedy for cheapness, and beware of being deceived.