How to Identify a Steel Alloy by Chemical Composition

Steel is an alloy, not a pure substance.

Several elemental metals are contained within metal and steel alloys. An alloy is not a compound, however, because the atoms of the different metals are not bonded together. Instead, they are mixed homogeneously in fixed ratios. For instance, common yellow brass is a homogeneous mixture of 67 parts copper to 33 parts zinc. To identify an alloy by its chemical composition, you simply need to consult a reference that shows alloys and their compositions.

Instructions

1. Write the chemical composition for the alloy that you are trying to identify. For example, imagine that you are trying to find the name of the alloy that is 99 parts iron to 1 part carbon.

2. Consult a Periodic Table of the Elements to find the chemical symbols for each element in your alloy. In this example, the symbol for iron is Fe and the symbol for carbon is C.

3. Find the chemical composition on a chart that lists alloys and their compositions. The chart below lists several common alloys and their compositions; you can find a more complete one through the link in the References section.

   Composition // Alloy
   99Fe, 1C // Steel
   67Cu, 33Zn // Yellow brass
   85Cu, 15Zn // Red brass
   88Cu, 10Sn, 2Zn // U.S. Government standard bronze
   85Sn, 6.8Cu, 6Bi 1.7Sb // Pewter
   88Sn, 8Pb, 4Cu, 0.5Sb // Tinfoil

   From this chart, you can identify the alloy from the example as steel.

References

• California State University: Allows and their Compositions

Resources

• Periodic Table of the Elements
• California State University: Allows and their Compositions