A) When the surface of stainless steel brown rust (points), people were very surprised: that "stainless steel is not rust, rust is not stainless steel, the steel may be a problem." In fact, this is a lack of understanding of a stainless steel one-sided view of the error. Stainless steel under certain conditions will be rusty. Stainless steel has the ability to resist atmospheric oxidation of stainless steel --- that is, but also with the acid, alkali and salt corrosion medium is the ability --- that is corrosion resistance. However, the size of its corrosion resistance is with its own chemical composition of steel, plus each state, using the media type and environmental conditions change. Such as 440c steel, in a clean dry atmosphere, there is absolutely excellent anti-corrosion ability, but will move it to the waterfront, contains a lot of salt in the sea mist, and soon will rust, so, not any kinds of stainless steel, the corrosion capability under any circumstances, does not rust. Stainless steel is by its very thin surface layer of fine solid and stable chromium-rich oxide layer (protective film), to prevent the continued infiltration of oxygen atoms, to oxidation, and access to anti-corrosion ability. If there is some reason, this film was the constant destruction, air or liquid oxygen or metal atoms will continue to penetrate the iron atom out from the constant analysis of the formation of loose iron oxide, metal surface corrosion will be constantly . This surface film in the form of a lot of damage, more common in everyday life are summarized as follows: 1 stainless steel surface deposit product with other metals containing dust particles or heterogeneous metal fixtures in the humid air, fixtures between the condensate and stainless steel, the two together into a micro-cell, triggering the electrochemical reaction, protective film is damaged, call it that electrochemical corrosion. 2 stainless steel surface adhesion of organic juice (such as vegetables, soup, sputum, etc.), the case of oxygen in water to form organic acids, organic acids long is the corrosion of metal surfaces. 3 stainless steel surface adhesion containing acid, alkali, salts (such as a wall decoration lye, lime splash), causing localized corrosion. 4 in a polluted air (such as rich in sulfide, carbon dioxide, nitrogen oxide atmosphere), the case of condensation of water to form sulfuric acid, nitric acid, acetic acid solution point, causing chemical corrosion. Above the surface protective film may cause damage to stainless steel caused by corrosion. Therefore, in order to ensure a permanent bright metal surface, not rusty, we recommend: 1. Must always clean the surface of the decorative stainless steel scrub to remove attachments, eliminate triggering modification of external factors. (2) Stainless steel 316 coastal areas resistant to seawater corrosion.

B) What little magnetic stainless steel bearings?

Due to the recent sustained high nickel prices, such as Ni 304 series stainless steel high production costs, hence, have excellent corrosion resistance and a very attractive price of 400 series stainless steel in a product promotion becomes increasingly urgent. Major domestic steel plant in order to reduce the production costs of downstream customers, improve the market competitiveness of the end product, increased the nickel-free or low-nickel stainless steel R & D and marketing efforts, 440 series stainless steel for many users the inherent magnetic prohibitive.
In real life, most people think that stainless steel is not magnetic, and with the magnet to identify stainless steel, this approach is very scientific. First, zinc alloy, copper alloy can generally imitate the appearance of stainless steel color, there is no magnetic, easily mistaken for stainless steel; and even if we are the most frequently used 304 steel, after cold working, he will be varying degrees of magnetic . It is not just by a magnet to determine the authenticity of stainless steel.
So how did the magnetic stainless steel come from?
According to material physics research, from the electron spin magnetic metal structure, electron spin are quantum-mechanical properties, either "up" can also be "down." In ferromagnetic metals, electronics will automatically follow the same direction of rotation, while the anti-ferromagnetic metals, some electronic accordance with the rules of the model, while the adjacent electrons moving in the opposite direction or anti-parallel spin, but for the triangular crystal in electronic format, because each triangle of the two electrons must spin in the same direction, so the spin structure no longer exists.
In general, austenitic stainless steel (as represented by 304) is non-magnetic, but also may carry a weak magnetic, while ferritic (mainly 430,409 L, 439, and 445NF) and martensite (to 410 represented) are generally with magnetic.
There are some kinds of stainless steel (such as 304, etc.) are classified as "non-magnetic stainless steel" refers to a value below its magnetic indicators only, that is, generally stainless steel with a certain more or less magnetic.
In addition, the above-mentioned non-magnetic or weak austenite is magnetic, while the ferrite and martensite is magnetic, because smelting composition segregation or improper heat treatment, can cause a small amount of austenitic 304 stainless steel in the Markov body or ferrite, so that there will be 304 stainless steel in weakly magnetic. In addition, 304 stainless steel after cold working, organizational structure will transform to martensite, the greater the cold deformation, martensitic transformation, the more magnetic will be stronger.
Want to completely eliminate the magnetic 304 stainless steel, high temperature solution treatment can restore stable austenite, thereby eliminating magnetic.
Therefore, the magnetic material is arranged by the molecular and electronic spin are the same rules of sexual decision, we believe that the physical properties of the material, and corrosion resistance of materials is determined by the material's chemical composition, is the material's chemical performance has nothing to do with whether the material is magnetic.
From stainless steel development perspective, 440 instead of 304 lines can be described as trend. The 200 series material as scrap recycling is facing many difficulties, is non-environmentally friendly stainless steel, if the increased use of the steel, the stainless steel industry is not conducive to sustainable development, so many large companies have the foresight to 200 systems that No, the sights on the more potential for development of the 400 series stainless steel.

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