Steel pipes can be divided into carbon pipes and alloy pipes, stainless steel pipes and so on. Carbon pipes can also be divided into ordinary carbon pipes and high-quality carbon construction pipes. Alloy pipes can be divided into low alloy pipes, alloy construction pipes, high alloy pipes, high strength pipes. Bearing pipes, heat and acid resistant stainless pipes, fine alloy (such as Kovar alloy) pipes and superalloy pipes, etc.
Stainless steel square pipes in steel pipes are generally referred to as stainless steel square pipes and acid-resistant steel. Stainless steel square pipe refers to the steel which is resistant to the corrosion of weak medium such as atmosphere, steam and water, while acid-resistant steel refers to the steel which is resistant to the corrosion of chemical etching medium such as acid, alkali and salt.
The stainless square tube has a history of more than 90 years since its appearance at the beginning of this century. The creation of stainless steel square pipes is a serious achievement in the world metallurgical history. The development of stainless steel square pipes has laid an important material and technological foundation for the development of modern industry and scientific and technological progress. There are many kinds of stainless steel square pipes with different properties, which gradually constitute several categories in the process of development.
According to the structure, it can be divided into four categories: martensitic stainless steel square pipe (including precipitation hardening stainless steel square pipe), ferritic stainless steel square pipe, austenitic stainless steel square pipe and austenitic and ferritic duplex stainless steel square pipe; chromium stainless steel square pipe can be divided into chromium stainless steel square pipe according to the main chemical composition of steel or some characteristic elements of steel. The stainless steel square pipes are chromium-nickel stainless steel square pipes, chromium-nickel-molybdenum stainless steel square pipes, low-carbon stainless steel square pipes, High-Molybdenum stainless steel square pipes and high-purity stainless steel square pipes. According to the performance characteristics and use of steel, the steel can be divided into nitric acid-resistant stainless steel square pipes, sulfuric acid-resistant stainless steel square pi Stainless steel square pipe, etc. According to the functional characteristics of steel, it can be divided into low-temperature stainless steel square pipe, non-magnetic stainless steel square pipe, free-cutting stainless steel square pipe, superplastic stainless steel square pipe, etc. At present, the commonly used classification methods are classified according to the structure characteristics of steel, the chemical composition characteristics of steel and the separation of the two methods. Generally, it can be divided into martensitic stainless steel square pipe, ferritic stainless steel square pipe, austenitic stainless steel square pipe, duplex stainless steel square pipe and precipitation hardening stainless steel square pipe, or chromium stainless steel square pipe and nickel stainless steel square pipe.
Steel grades and specifications of steel pipe products are extremely diverse, and their performance requirements are also various. All these should be distinguished according to the user's request or the change of working conditions. Generally, steel pipe products are classified according to section shape, consumption method, pipe material, connection mode, plating characteristics and use.
Stainless iron is chromium-free and nickel-free, also known as Cr stainless steel, which has certain anti-corrosion ability. Stainless iron is not a colloquial saying. It is superficially thought that stainless steel with ferromagnetism mainly refers to 1Cr17 (ferrite) series and 1Cr13 (martensite) series, while Fe does not have ferromagnetism when it exists as austenitic stainless steel sheet. It is easy to be misunderstood to distinguish Ni/Cr in this paper, although they cause isomerism of Fe. But Fe and Ni are ferromagnetic and Cr is paramagnetic. Many of the 1J series of high performance soft magnetic data are Ni-based.
Compared with stainless steel, stainless steel mainly depends on whether it contains nickel. Stainless iron generally refers to S US430 in Japan and 1Cr17 in China. Its main chemical composition is C:<0.12, Si:<0.75, Mn<1.00, P:<0.035, S<0.030, Ni:<0.60, and Cr:16.00-18.00 as ferritic stainless steel.
Stainless steel contains both chromium and nickel. Because nickel is a stable element, its corrosion resistance is naturally much stronger than that of stainless steel.
Because of the high price of nickel, the cost of stainless steel is higher than that of stainless steel, and the difference of corrosion resistance makes the price of stainless steel 1/4-1/3 higher than that of stainless steel.