Why can stainless steel rust? Can you also take magnetism?

Why can stainless steel rust? Can you also take magnetism?

When stainless steel tubal appearance presents Brown rusty spot (dot) time, everybody feels open-eyed greatly: Think " stainless steel is rustless, rusting is not stainless steel, the likelihood is steel presented a problem character " . Original, this is a kind of when lack understanding to stainless steel one-sided fault point of view. Stainless steel also can rust below sure condition

Stainless steel has the ability that defends atmosphere oxidation---Do not become rusty namely quality, also have the ability that corrodes therefore in the medium that containing acerbity, alkaline, salt at the same time---Be able to bear or endure namely corrode sex. But its fight the large and small that corrodes ability is therewith steel pledges oneself chemistry is formed, the state that add each other, apply what the condition reachs environmental medium kind and alter. Be like 304 steel tube, be in as dry as a chip in the air that clean, affirmation fights rustily ability outstandingly, but move it littoral area, in the sea fog that contains a lot ofa lot of salt portions, can rust very quickly; And 316 steel tube are reflected crackajack. Consequently, not be a kind of any stainless steel, fall in any environments can anti-corrosive, rustless.

Stainless steel is to rely on its appearance to form a paper-thin and consolidate close smooth and steady Fu Ge oxidizes film (defend film) , avoid oxygen atomic to be entered continuously, oxidize continuously, and obtain fight rustily ability. Once have some kind of factor, this kind of film sufferred damage ceaselessly, atom of the oxygen in air or liquid can be entered ceaselessly or the iron in the metal is atomic ceaselessly analyse leaves come out, form loose ferric oxide, metallic appearance also suffers ceaselessly rustily. The kind that this kind of outside film damages a lot of, see more in daily life have a few kinds as follows

Appearance of 1. stainless steel retains the attachment that accumulating the dust that contains a lot ofother tantalum or alien metal grain, in humid air, the condenser water between attachment and stainless steel, become both a small cell repeatedly, caused electrochemistry reaction, diaphragm suffers damage, say call electrochemistry is corroded.

Conglutinate of appearance of 2. stainless steel has machine content juice (the dish that be like melon, water in which noodles have been boiled, phlegmy etc) , below state of oxygen having water, make organic acid, long-term an organic acid is outside to the metal corrode.

Conglutinate of appearance of 3. stainless steel contains a lot ofacerbity, alkaline, salt kind material (if decorate splash of the buck of metope, limewater) , bring about isolated corrosion.

4. is in the air that has pollution (if contain a lot ofthe air of nitrogen of carbon of a lot of sulfide, oxidation, oxidation) , treat condenser water, make point of fluid of vitriolic, nitric acid, acetic acid, bring about chemistry to corrode.

Above state all can form stainless steel appearance to defend velar attaint is caused rustily. So, belong to outside and abiding light for bail, not by rustily, we advocate:

1. is necessary to often undertake cleaning wiping to decorating stainless steel appearance, purify attachment, remove the outside essential factor that causes retouch.

2.Littoral area should use stainless steel of 316 raw material, 316 raw material can revolt seawater to corrode.

Some stainless steel are in charge of chemical composition to cannot agree with corresponding state level on 3. market, short of requirement of 304 raw material. Also can bring about consequently rusty, this chooses the merchandise that has promise manufacturer carefully with respect to demand user.

Why can stainless steel also take magnetism?

Big the daily life of a family thinks magnet is adsorptive stainless steel material, test and verify its stand or fall and true bogus, do not suck without magnetism, thinking is good, renown carbon comes; The person that suck has magnetism, thinking is pinchbeck fake. Original, this is a kind of extreme is one-sided, the divisional method of unrealistic fault.

The phyletic heavy and complicated of stainless steel, can divide by arrangement construction below normal temperature it is a few kinds:

1. Austenite: Be like 201, 202, 301, 304, 316 etc;

2. Martensite or ferrite: Be like 430, 420, 410 etc;

Austenite it is not to have magnetism or weak magnetism, martensite or ferrite are magnetic.

Use as commonly the stainless steel majority that decorates tube plate is austenite model 304 raw material, will tell commonly do not have magnetism or weak magnetism, but because take exercise to form chemical composition to shake or machine a state to differ,present magnetism possibly also, but it is pinchbeck that this cannot think or unqualified, what element is this?

Austenite is being mentioned above is not to have magnetism or weak magnetism, and martensite or ferrite take magnetism, slant because of the composition when taking exercise analyse or heat treatment misgivings, can form austenite martensite of the minority in 304 stainless steel or ferrite arrangement. So, puny magnetism can be contained in 304 stainless steel.

Other, 304 stainless steel pass cold working, arrangement constructs to also can be changed to martensite, cold working is out of shape degree bigger, martensite is changed more, the magnetism of steel is bigger also. Be like the metal strip of one lot number, produce 76 canals of Φ , without showing magnetism sense, produce 9.5 canals of Φ . Because Ling turn is out of shape bigger magnetism feels,showing a few, produce square rectangular canal because deflection is bigger than round canal, especially knuckle part, be out of shape more intense magnetism more showing.

Want the magnetism of the 304 steel that afore-mentioned elements form comb-out, can be in sleave to restore smooth and steady austenite to arrange through tall Wen Gurong, next expunction is magnetic.

Fastening what should put forward is, because of above the magnetism of the 304 stainless steel that the element forms, with the stainless steel of other raw material, be like 430, the magnetism of carbolic steel is not same level thoroughly other, that is to say what the magnetism of 304 steel shows from beginning to end is weak magnetism.

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