Aviation Structural Mechanic (AM) Strand Practice Exam 2026 - Free Practice Questions and Study Guide

Heat treatment changes aluminum alloy properties by altering the metal’s microstructure. In airframe alloys, especially precipitation-hardening types, applying heat treatment changes strength, hardness, and ductility. As the alloy is aged or peak-aged, fine precipitates form that hinder dislocation motion, boosting yield strength and hardness while reducing ductility. The final state is described by the temper, and that temper directly reflects the mechanical properties and, in many cases, influences corrosion resistance. So, heat treatment can increase strength and hardness and alter ductility, with the temper designation guiding the expected performance. This is why it isn’t about color changes, weight change, or completely eliminating corrosion—the primary effects are on mechanical properties and how corrosion resistance behaves in the tempered state.