This presentation will provide the non-metallurgist with a basic understanding of carbon and low alloy steels. First we'll describe the carbon and low alloy steels by examining the iron-carbon binary phase diagram and understand the basic microstructures as related to carbon content. We'll discuss the nomenclature of the different carbon and alloy steel groups. We will then examine how mechanical properties are influenced through carbon content, alloy additions and heat treatment. We will also discuss the differences in carbon and low alloy steels that are specified as structural steels and high strength-low alloy (HSLA) steels. Finally, we will address the issues of material selection, processing and finishing.