Stainless steel definition: A high alloy steel that resists corrosion in air or chemically corrosive media

Two. Stainless steel principle: There is only one element that determines the properties of stainless steel. This is chromium. Each stainless steel contains a certain amount of chromium. So far, there is no chromium.

stainless steel. The reason why chromium has become the main element determining the performance of stainless steel is that it can promote the electricity of iron-based solid solution after adding chromium as an alloying element to steel.

The polar potential is increased, and the electrons that absorb iron passivate the iron, and a very thin chromium film is formed on the surface to separate the oxygen intruding into the steel to resist corrosion damage.

Three. High alloy properties: In order to maintain the corrosion resistance inherent in stainless steel, steel must contain more than 12% chromium.

Four. Stainless steel type:

A wide variety of stainless steels can be divided into several categories according to organizational structure at room temperature:

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

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

V. Why does stainless steel also conduct magnetism?

People often think that magnets can be used to adsorb stainless steel, which can verify its pros and cons and authenticity. It does not absorb non-magnetic, and it is considered to be good. It is genuine and genuine; if the person is magnetic, it is considered to be a counterfeit fake

. In fact, this is an extremely one-sided, unrealistic way of distinguishing mistakes.

The austenite type is non-magnetic or weakly magnetic, and martensite or ferrite is magnetic.

The stainless steel usually used as the decorative tube sheet is mostly austenitic type 304 material, which is generally non-magnetic or weakly magnetic, but the chemical composition fluctuates or the processing state is not caused by smelting

Magnetism may also occur, but this cannot be considered as a counterfeit or unqualified. For example, 304 stainless steel is cold worked, and the microstructure is also transformed into martensite. The degree of cold work deformation is more

Large, the more martensite transformation, the greater the magnetic properties of steel. Like a batch of steel strip, production & Phi; 76 tube, no obvious magnetic sense, production & Phi; 9.5 tube. Large magnetic sensation due to bending deformation

It is obvious that the rectangular tube produced by the square is larger than the round tube, especially the angled portion, and the deformation is more intense and the magnetic is more obvious.

Specially, the magnetic properties of 304 stainless steel caused by the above reasons are not at the same level as the magnetic properties of other materials such as 430 and carbon steel, if

Stainless steel with weak magnetic or no magnetic, should be judged as 304 or 316 material; if it is the same as the magnetic properties of carbon steel, it should be judged as not 304 material.

Six. Why does stainless steel rust?

When brown rust spots (dot) appear on the surface of stainless steel pipes, people are very surprised: think that stainless steel is not rusting, rust is not stainless steel, it may be steel

There was a problem”. In fact, this is a one-sided misconception about the lack of understanding of stainless steel. Stainless steel will also rust under certain conditions. Stainless steel has resistance

The ability of atmospheric oxidation - that is, rust, and also has the ability to corrode in the medium containing acid, alkali, salt - that is, corrosion resistance. But the size of its corrosion resistance is with it

The chemical composition of the steel itself, the state of addition, the conditions of use, and the type of environmental medium. Such as 304 steel pipe, in the dry and clean atmosphere, there is absolutely excellent corrosion resistance

Capability, but moving it to the beachfront, it will soon rust in sea fog with a lot of salt; and 316 steel pipe is doing well. Therefore, not any kind of stainless

Steel, resistant to corrosion and rust in any environment.

Stainless steel is a very thin and strong and stable chromium-rich oxide film (protective film) formed on the surface to prevent the oxygen atoms from continuing to infiltrate and continue to be oxidized.

The ability to rust. Once for some reason, the film is continually destroyed, oxygen atoms in the air or liquid will continue to infiltrate or iron atoms in the metal will continue to separate out.

Coming, forming loose iron oxide, the metal surface is constantly rusted.

When stainless steel surfaces contain dust or other metal particles attached to other metal elements, in humid air, the condensation between the attached material and the stainless steel will be two.

There is a micro-battery that triggers an electrochemical reaction, and the protective film is destroyed. It is called electrochemical corrosion, the actual life, the metal corrosion in engineering practice, the vast majority

are all electrochemical corrosion.

VII. Product Features and Uses

SUS304: It has good corrosion resistance, heat resistance, low temperature strength and mechanical properties, good hot workability such as stamping and bending, no heat treatment hardening, and no magnetism. Widely used in home

Houseware (1, 2 food utensils), cabinets, indoor pipelines, water heaters, boilers, bathtubs, auto parts, medical equipment, building materials, chemicals, food industry, agriculture, ships

Parts.

SUS304L: Austenitic basic steel, the most widely used; excellent corrosion resistance and heat resistance; excellent low temperature strength and mechanical properties; single-phase austenitic structure, no heat treatment.

Chemical phenomenon (non-magnetic, use temperature -196--800 °C).

SUS304Cu: Austenitic stainless steel with 17Cr-7Ni-2Cu as the basic composition; excellent formability, especially wire drawing and anti-aging cracking; - corrosion resistance is the same as 304.

SUS316: Excellent corrosion resistance and high temperature strength, can be used under severe conditions, work hardenability, and non-magnetic. Suitable for seawater equipment, chemicals, dyes, paper,

Oxalic acid, fertilizer production equipment, photography, food industry, coastal facilities

SUS316L: Mo (2-3%) is added to steel, so corrosion resistance and high temperature strength are excellent; SUS316L has lower carbon content than SUS316, so it is better than intergranular corrosion resistance than SUS316

; high temperature creep strength. It can be used under severe conditions, work hardenability and non-magnetic. Suitable for seawater equipment, chemicals, dyes, paper, oxalic acid, fertilizer production equipment

, photography, food industry, coastal facilities

SUS321: Ti is added to 304 steel, so it is excellent in intergranular corrosion resistance; high temperature strength and high temperature oxidation resistance are excellent; cost is high, and workability is inferior to SUS304. Heat resistant materials, steam

Cars, aircraft exhaust pipe lines, boiler covers, pipes, chemical plants, heat exchangers.

SUH409H: Good processability, good weldability, high temperature oxidation resistance, and temperature range from room temperature up to 575 °C. Widely used in automobile exhaust system

Unification.

SUS409L: Controls the C and N contents in steel, so it is excellent in weldability, formability and corrosion resistance; contains 11% Cr, ferritic stainless steel with BCC structure at high temperature and normal temperature;

Due to the filling of Ti, there is vacancy and corrosion resistance below 750 °C.

SUS410: Martensite represents steel grade, high strength, high hardness (magnetic); poor corrosion resistance, not suitable for use in severe corrosive environments; low C content, good processability,

The surface is hardened by heat treatment.

SUS420J2: Martensite represents steel grade, high strength, high hardness (magnetic); poor corrosion resistance, poor formability, good wear resistance; capable of heat treatment to improve machinery

Performance. Widely used in processing tools, nozzles, valves, rulers, utensils.

SUS430: Low thermal expansion rate, good molding and oxidation resistance Suitable for heat-resistant appliances, burners, home appliances, food utensils, kitchen sinks. Low price and good processability

The ideal alternative to SUS304; good resistance to mile corrosion, typical non-heat treated hardenable ferritic stainless steel. Simplified Chinese, click the Convert button to convert to Traditional

word.