Metals as alloys of more than one chemical element differ from each other primarily in the chemical composition. Therefore the determination of the chemical composition is the first step in the classification of metals (alloys). But this is not enough for a complete classification (determination of the exact class) of metals –alloys. The exact classification of a metal is defined in appropriate standard of materials. Except the chemical composition for each particular material, these standards also define other requirements (most often mechanical properties) that a metal of the corresponding class should satisfied.
So for determination of exact grade of a metal the next testing should be performed:
- chemical analysis for determination of chemical composition,
- tensile testing and/or hardness testing for determining the basic mechanical properties.
In some cases it is needed to determine additional mechanical properties (for example creep properties or dynamic properties or similar) if appropriate standards are prescribed such properties. Sometimes on the base of special requirements of a customer the metallographic analysis should be performed to define some microscopic characteristic of the metal-alloy.
Determining of the chemical composition of an alloy (metal) is not simple process. It is necessary to have test equipment, appropriate method and trained staff. There are large number of standards that prescribe the method of the chemical composition determining. Primary they are divided according to basic metal which is carrier of alloy and secondary in the group of alloys belonging to that alloy carrier.