Ferritic stainless steel

• Overview

  Ferritic stainless steel (400 series) contains 12%~30% chromium and has a body-centered cubic crystal structure. The steel is usually used to make parts resistant to atmospheric, water vapor, water and oxidizing acid. Ferritic stainless steel has proved to be an excellent alternative material in many applications where austenitic stainless steel (300 series) was previously considered the only option. Ferritic stainless steel does not contain nickel, the main element is chromium and iron, and sometimes small amounts of Mo, Ti, Nb, etc. Chromium is a particularly corrosion-resistant element in stainless steel.

• Advantages

  Ferritic stainless steel at room temperature, its microstructure is ferritic, it has a strong magnetic, can not be hardened by quenching method. Compared with austenitic steel, ferritic stainless steel has high thermal conductivity, small specific resistance, small expansion coefficient, good oxidation resistance, excellent stress corrosion resistance, and it is not sensitive to chloride stress corrosion cracking. In addition, since of higher chromium and molybdenum, it has good pitting corrosion resistance and crevice corrosion resistance. Since of no valuable element like nickel, it is usually cheap.

• Shortage

  Ordinary ferritic stainless steel has the disadvantages of low temperature brittleness and room temperature brittleness, notch sensitivity, high intergranular corrosion tendency, poor weldability and so on. These deficiencies are related to the purity of steel, especially the high content of carbon, nitrogen and other interstitial elements in steel. As long as the carbon and nitrogen in steel are low enough, the above shortcomings can be overcome basically. Smelting technology, especially the development of vacuum metallurgy and secondary refining process, has been able to produce high purity ferritic stainless steel with very low carbon and nitrogen, which makes this kind of steel widely used in industry.

• Classification

  Ferritic stainless steel can be divided into low chromium, medium chromium and high chromium stainless steel according to the chromium content.

  According to the purity of steel, especially the content of carbon and nitrogen impurities, it can be divided into ordinary ferritic stainless steel and high pure ferritic stainless steel.

• Common grades

  TP429 (S42900)

  TP430 (1Cr17, S43000)

  TP444 (S44400, 18Cr-2Mo)

  TP446 (S44600)

  TP XM-27 (S44627)

  TP XM-33 (S44626)