Ferrous vs. non-ferrous classification, the alloy systems behind carbon and low-alloy steel, stainless steel, aluminum, and titanium, and the physical mechanisms — solid-solution strengthening, precipitation hardening, and grain refinement — that let alloying elements actually change a metal's properties.
This module is the first of four back-to-back material-class modules, applying Module 1's metallic bonding and Module 2's crystal structures at full width. It starts with the ferrous-versus-non-ferrous classification line, then works through carbon and low-alloy steel, the three stainless steel families, aluminum's wrought alloy series and precipitation hardening, and titanium's alpha, beta, and alpha-beta alloy systems — closing with the strengthening mechanisms common to all of them.
By the end of this module you should be able to read an alloy designation like 4140 or 6061-T6 as a short list of deliberate, individually-justified property adjustments, and explain why every strengthening mechanism trades away some ductility in return — a trade-off Module 14's material selection module and Module 9's heat treatment module both build on directly.