How to distinguish the stainless steel varieties?

- Nov 22, 2017 -

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

1. Austenite size (300 series, cr ~ nickel) : 304, 321, 316, 310, etc., 200 is low nickel

Economical stainless steel, also is austenite;

2. Martensite or ferritin type (400 series) : such as 430, 420, 410, etc. Austenite is not magnetic or magnetic, but martensite or ferrite is magnetic.

Hardware products should consider his anti-rust, hardness, processing performance, etc.,  201, 202, 301, 304, 316 in anti-rust, heat resistance, toughness in turn ascending. 202, 304, 316 corresponding density: 7.74, 7.93, 7.98. The 316 stainless steel plate is the U.S. standard.


Stainless steel pipes

The commonly used stainless steel are 201 and 304. The actual ingredients are different

The 304 stainless steel is the most widely used. It is austenitic stainless steel.

The 400 series are martensitic stainless steel.

304 stainless steel without magnetism, the 400 series are magnetic. But some 304 stainless steel can suck the iron out, because the magnet can feel micromagnetism. Compared to 400 series, the nickel content of 304 is higher, about 8-10%.


400 series stainless steel, this kind of stainless steel inner tissue is tempered martensite, with the magnetic conductivity, can be attracted by the magnet

Lead. Austenitic stainless steel has no magnetic absorption, its typical representative is 304 # stainless steel, but this kind of stainless steel can't with flexible heat treatment with high strength, nonmagnetic austenitic stainless steel can't with flexible heat treatment with high strength, nonmagnetic austenitic stainless steel is not used in the manufacture of the blade, blade knife, knife seat, etc.


Therefore, it is not easy to use magnetic to indicate whether it is stainless steel. The chromium content of 400 series stainless steel is lower than 300 series stainless steel, but not like 300 series carbon deposition, and can be used as heat treatment, can be used in the high temperature of 1200F (393 degrees Celsius) work environment, to increase its hardness.


The 400 series of ferrite and martensite stainless steel, like 410 is a kind of 400 series stainless steel. Generally 304 will be better, but in part of  rust, corrosion resistance and other special places, 410 is better than 304. For example, some of them require high hardness but do not require good rust resistance and do not require corrosion resistance, so 410 is much better. The 400 series of stainless steel can be improved by heat treatment. Now, the 400 series of tableware is used for low-end products and 304 for high-end products.


stainless steel tubes

300 series - chromium-nickel austenitic stainless steel:

Model 301- malleable, used in molding products. Rapid hardening-can also be made through mechanical processing. Good weldability-the abrasion resistance and fatigue strength are superior to 304 stainless steel.

Model 302 - corrosion resistance like 304, due to high carbon content and therefore stronger strength.

Model 303 - makes it easier to machining by adding a small amount of sulfur and phosphorus to 304.

Model 304 - general model;It is 18/8 stainless steel. GB is 0Cr18Ni9.

Model 309 - better temperature resistance than 304.

Model 316 - after 304, the second most widely used type of steel, mainly used in food industry and surgical equipment, added molybdenum elements to give it an anti-corrosion special structure. It is also used as "Marine steel" because of its good anti-chloride corrosion capability compared with 304

Model 321 - except for the addition of titanium to reduce the risk of corrosion of the weld seam, other performance is similar to 304.


304 stainless steel pipe

400 series - ferrite and martensite stainless steel:

Model 408 - good heat resistance and weak corrosion resistance, 11% Cr, 8% Ni.

Model 409 - cheapest model (British and American), usually used as a car exhaust pipe, is ferritic stainless steel.

Model 410 - martensite (high strength chromium steel), good wear resistance and less corrosion resistance.

Model 416 - added sulfur improves the processing performance of the material.

Model 420 - "blade grade" martensitic steel, the earliest stainless steel, such as brinell high chromium steel. Also used in surgical tools, which can be very bright.

Model 430 - ferritic stainless steel, decorative use, for example, for car accessories. It is well formed, but it is poor and resistant to corrosion.

Model 440 - high strength cutting steel with slightly higher carbon content.  After proper heat treatment, high yield strength can be obtained. The hardness can reach 58HRC, which belongs to the most hardened stainless steel column. The most common example of this is shaving. There are three commonly used models: 440A, 440B, 440C, and 440F (easily processed).

Edit by Ms. Julia Zhu of KRM/BSW (Sales Dept.)

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