The alloy steel is part of engineering steels courses. The engineering steels is part of the steel applications set of courses. In this course, an introduction to alloy steel help you to understand the alloy steel application and its mechanical properties. After that, the low carbon steel will be developed. Different alloys elements will be evaluated and the classical TTT diagrams will be described. In the next module, medium carbon steels will be described. Finally, the properties of quenched and tempered steels will be developed. The tempering curve will be evaluated for different alloying element additions and the properties of quenched and tempered steels will be outlined.