Steels can be classified by a variety of different systems depending on:

• The composition, such as carbon, low-alloy or stainless steel.
• The manufacturing methods, such as open hearth, basic oxygen process, or electric furnace methods.
• The finishing method, such as hot rolling or cold rolling
• The product form, such as bar plate, sheet, strip, tubing or structural shape
• The deoxidation practice, such as killed, semi-killed, capped or rimmed steel
• The microstructure, such as ferritic, pearlitic and martensitic
• The required strength level, as specified in ASTM standards
• The heat treatment, such as annealing, quenching and tempering, and thermomechanical processing
• Quality descriptors, such as forging quality and commercial quality.