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Advantages of using ductile iron in valve manufacturing

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  • Time of issue:2020-11-03
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(Summary description)      As a substitute for steel, mankind developed ductile iron in 1949. The carbon content of cast steel is less than 0.3%,

Advantages of using ductile iron in valve manufacturing

(Summary description)      As a substitute for steel, mankind developed ductile iron in 1949. The carbon content of cast steel is less than 0.3%,

  • Categories:Company News
  • Author:
  • Origin:
  • Time of issue:2020-11-03
  • Views:0

      As a substitute for steel, mankind developed ductile iron in 1949. The carbon content of cast steel is less than 0.3%, while the carbon content of cast iron and ductile iron is at least 3%. The low carbon content in cast steel prevents the carbon present as free graphite from forming structural flakes. The natural form of carbon in cast iron is in the form of free graphite flakes. In nodular cast iron, this graphite flake is transformed into tiny spheres through a special treatment method. This improved sphere makes the spheroidal graphite cast iron have more excellent physical properties than cast iron and steel. It is the spherical microstructure of this carbon that makes ductile iron have better ductility and impact resistance, while the form of flakes inside the cast iron causes the cast iron to have no ductility. The best ductility can be obtained through the ferrite matrix.
      Therefore, after the pressure-loading parts of ductile iron are processed by the process of ferritizing annealing cycle, the spherical structure inside the ductile iron can also eliminate the cracking phenomenon that the flake graphite inside the cast iron is easy to produce. In the microphotograph of ductile iron, the cracks can be seen to terminate after reaching the graphite ball. In the ductile iron industry, these graphite balls are called "crack terminator" because of their ability to prevent fracture.
      Compared with cast iron, ductile iron has an absolute advantage in strength. The tensile strength of ductile cast iron is 60k, while the tensile strength of cast iron is only 31k. The yield strength of spheroidal graphite cast iron is 40k, while the cast iron does not show the yield strength and eventually fractures. The strength-to-cost ratio of ductile iron is much better than that of cast iron.
      The strength of ductile iron is comparable to that of cast steel. Nodular cast iron has a higher yield strength, with a minimum yield strength of 40k, while the yield strength of cast steel is only 36k. In most municipal applications, such as water, salt water, steam, etc., the corrosion resistance and oxidation resistance of ductile iron exceed those of cast steel. Due to the nodular graphite microstructure of nodular cast iron, nodular cast iron is better than cast steel in terms of reducing vibration ability, so it is more conducive to reducing stress. An important reason for choosing ductile iron is that ductile iron is less expensive than cast steel. The low cost of ductile iron makes this material more popular, higher casting efficiency, and less machining costs for ductile iron.  

Wenzhou Kaishimu Valve Industry Co., Ltd.

Building 2, No. 696, Binhai Fifth Road, Wenzhou Economic and Technological Development Zone, Zhejiang

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Wenzhou Kaishimu Valve Industry Co., Ltd.
Wenzhou Kaishimu Valve Industry Co., Ltd.

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