Chemical Composition of Cast Iron and Cast Steel

Why is it important to control the chemical composition of metal castings?

The chemical components of metal castings including normal Carbon (C), Silicon (Si), Manganese (Mn), Sulfur (S), Phosphorus (P), and also including many alloy components, such as Chrome (Cr), Molybdenum (Mo), Nickel (Ni), Copper (Cu) etc.

Different chemical components have different functions, so caused the very different mechanical properties, such as increasing their tensile strength, hardness, abrasive resistance and corrosion resistance. This is why we need to consider the chemical composition.

Chemical Composition of Cast Iron, Grey Iron and Ductile Iron

As for the alloy cast iron, the chemical composition, especially the alloy content, is very important. There will be big risk or malfunction if the alloy content can not meet the requirements.

As for normal grey iron and ductile iron, the chemical composition is not important comparatively. The iron foundries could adjust the compositions according to their experience as long as they could meet the physical and mechanical requirements. However, by principle, the Sulfur should be controlled in the reason range, too much sulfur will cause fragile of iron castings.

Chemical Composition of Cast Steel, Carbon Steel and Alloy Steel

Chemical composition is very important for steel castings, as for the most of steel castings, as long as the chemical composition is in the required range, then their mechanical properties should be qualified. Because most cast steel should meet some special properties besides of tensile strength and elongation, so chemical composition will be the most important inspection.

How to inspect the chemical composition of cast iron and cast steel?

1. Chemical analysis method (chemical test method)

Suitable for both cast iron, cast steel and alloy steel materials. The accuracy of result depends on the skill of laboratory technician.

Shortcoming: Slow, so can not meet the requirements for inspection before and during production. Our foundry normally used this method to inspect the chemical composition of pig iron materials.

2. Chemical composition spectrometer

Suitable for both cast iron and cast steel, and also alloy steel. The accuracy and speed are very high, so good for inspection during production.
Shortcoming: If some chemical elements are very high or very low, then the result will not be accurate.

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