This book is a practical guide to alloyed cast irons, linking first-principles metallurgy to fast, defensible material choices. It explains how silicon shifts the stable (γ&graphite) and metastable (γ&Fe-C) eutectics and how graphite morphology, distribution, and size govern strength, toughness, damping, conductivity, wear, and thermal-shock behavior. A concise element-by-element map shows how Ni, Cr, Mo, Mn, Cu, Si, and Al control matrix type and TTT behavior, enabling pearlitic, bainitic, martensitic, or austenitic structures directly from the mold. The applied chapters compare major families-Ni-Tensil, bainitic/acicular, self-hardening, Silal/high-Si and Al+Si ferritic, Chugal, Duriron, Ni-Resist/Nicrosilal/Minvar/Nomag, and "white" irons such as Ni-Hard and high-chromium grades-with typical compositions, processing levers, properties, and use cases. Clear tables and rules of thumb translate microstructure talk into selection and troubleshooting steps. This book serves professional/practitioner readers and graduate students who must specify or diagnose components facing abrasion, corrosion, heat, or impact, solving the common gap between theory and shop-floor decisions.