Austenite forming ability = Ni% +30 C% +30 N% +0.5 Mn% +0.25 Cu% As can be seen from this equation : Carbon is a strong austenite -forming element , and its ability to form austenite is 30 times the nickel , but it can not be added to the corrosion-resistant stainless steel , because after welding it can cause sensitization and subsequent intergranular corrosion corrosion problems .

Ability to form nitrogen austenitic nickel is also 30 times , but it is a gas , want not cause porosity problems , can only add a limited amount of nitrogen in stainless steel . Adding manganese and copper can cause the steel making process to reduce refractory life and welding problems. Nickel can be seen from the equation , the addition of manganese is not very effective for the formation of austenite, but the manganese can add more nitrogen dissolved in the steel , and nitrogen is a very strong austenite-forming element. 200 series stainless steel , it is sufficient to use in place of nickel to manganese and nitrogen austenitic structure formed of 100% , the lower content of nickel , manganese , and the need to add igher quantities of nitrogen . 201 stainless steel, e.g. , containing only 4.5% of nickel , and contains 0.25% nitrogen . Nickel From these equations representing 7.5% of the nitrogen in the ability to form a nickel austenite , so the same can be formed of 100% austenitic structure . This is the principle of formation of 200 series stainless steel .

In some sub-standard 200 series stainless steel , because it is not adding sufficient quantities of manganese and nitrogen , in order to form a 100% austenitic structure , artificially reducing the amount of chromium , which will inevitably lead to a decrease in the corrosion resistance of stainless steel . In stainless steel , carbon seamless steel pipe manufacturer china there are two opposing forces simultaneously : ferrite forming elements constantly forming ferrite , austenite forming elements constantly forming austenite.

Depending on the final crystal structure of the relative number of two types of elements added . Chromium is a ferrite -forming element , the chromium crystal structure is formed on the stainless steel and austenite-forming element is a competition between . Because iron and chromium are ferrite forming elements , the 400 series stainless steels are fully ferritic stainless steel, magnetic. In the austenite forming elements - Nickel added to the Fe - Cr steel in the process, with the increase in nickel content , the formation of austenite will gradually increase until all ferritic structure have been transformed into austenite structure , thus forming a 300 series stainless steel. If only half the amount of Ni added will form 50% of ferrite and 50% austenite , this structure is called duplex stainless steel. 400 series stainless steel is an iron , carbon, chromium alloy .

This steel has a martensitic structure and iron , and therefore have a normal magnetic properties. 400 series stainless steel has a strong resistance to high temperature oxidation , and compared with steel , its physical and mechanical properties have further improved.

Most 400 series stainless steel can be heat treated . 300 series stainless steel is an alloy containing iron , carbon, nickel and chromium , a non -magnetic stainless steel , 400 series stainless steel has better than the malleable properties. As the 300 series austenitic stainless steel structure , so it has a strong resistance to corrosion in many environments , has broken a good anti- corrosion properties of metal super caused by stress-induced , and its material properties are not heat-treated affected.

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