Stainless Steel Pipe Tube Good corrosion resistance
Stainless steel is a 60 years of development of modern materials
Since the beginning of this century, since the invention of stainless steel, stainless steel put the image of modern materials and architectural applications in the excellent reputation in one, so that its competitors envy.
As long as the steel selection is correct, proper maintenance, stainless steel will not produce corrosion, pitting, corrosion or wear. Stainless steel or building materials with the highest strength of one of the materials. Because stainless steel has good corrosion resistance, it allows the structural parts to permanently maintain the integrity of the engineering design. Chromium-containing stainless steel also combines mechanical strength and high elongation in one, easy parts of the manufacturing, to meet the needs of architects and structural designers.
Why is corrosion resistant stainless steel? Stainless steel decorative tube, 201 stainless steel tube, 304 stainless steel tube
All metals react with oxygen in the atmosphere to form an oxide film on the surface. Unfortunately, the formation of iron oxide on ordinary carbon steel continues to oxidize, so that corrosion continues to expand, and ultimately the formation of holes. The surface of the carbon steel can be secured by painting with paint or oxidation resistant metals (eg zinc, nickel and chromium), but, as is known, this protection is only a film. If the protective layer is damaged, the following steel will begin to rust.
First of all, let's first understand what is stainless steel, popular point is not rusty steel is called stainless steel, but from the academic sense of resistance to air, steam, water and other weak corrosive media and acid, alkali, salt and other chemical erosion Corrosive steel. Also known as stainless acid resistant steel. Practical applications, often weak corrosive medium corrosion of steel known as stainless steel, and corrosion resistance of chemical corrosion of steel known as acid-resistant steel. Because of the difference in chemical composition between the two, the former is not necessarily resistant to chemical corrosion, while the latter are generally have a stainless steel. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel. Chromium is the basic element to obtain corrosion resistance of stainless steel, when the chromium content of steel to about 12%, chromium and corrosive media in the role of oxygen in the steel surface to form a thin layer of oxide film (self-passivation film) , Can prevent further corrosion of the steel matrix. In addition to chromium, the commonly used alloying elements are nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., to meet the various uses of stainless steel structure and performance requirements.
Stainless steel is usually divided into the base structure: 201 stainless steel tube, 304 stainless steel tube
Ferrite stainless steel. Contains 12% to 30% chromium. Its corrosion resistance, toughness and weldability with the increase in chromium content increased resistance to chloride stress corrosion resistance is better than other types of stainless steel.
② austenitic stainless steel. Containing more than 18% chromium, also contains about 8% of nickel and a small amount of molybdenum, titanium, nitrogen and other elements. Comprehensive performance is good, can withstand a variety of media corrosion.
③ austenitic - ferrite duplex stainless steel. Both the advantages of austenitic and ferritic stainless steel, and has a superplasticity. ④ martensitic stainless steel. High strength, but poor plasticity and weldability.
The corrosion resistance of stainless steel depends on chromium, but because chromium is one of the components of steel, so the protection method is not the same.
When the chromium content is 10.5%, the atmospheric corrosion resistance of the steel is significantly increased, but the chromium content is higher, although the corrosion resistance can be improved, but not obvious. The reason is that when the steel is alloyed with chromium, the type of surface oxide is changed to a surface oxide similar to that formed on pure chromium metal. This tightly adhered chromium-rich oxide protects the surface from further oxidation. This oxide layer is extremely thin, through which it can see the natural gloss of the steel surface, so that stainless steel has a unique surface. Moreover, if the surface damage, the exposed steel surface and the atmosphere will be self-repair, re-formation of this "passivation film", continue to play a protective role.