Malleable iron

Steels
Phases
Ferrite Austenite Cementite Martensite Graphite
Microstructures
Spheroidite Pearlite Bainite Ledeburite Tempered martensite Widmanstätten structures
Classes
Crucible steel Carbon steel Spring steel Alloy steel Maraging steel Stainless steel High-speed steel Weathering steel Tool steel
Other iron-based materials
Cast iron Gray iron White iron Ductile iron Malleable iron Wrought iron

Malleable iron is cast as white iron, the structure being a metastable carbide in a pearlitic matrix. Through an annealing heat treatment, the brittle structure as first cast is transformed into the malleable form. Carbon agglomerates into small roughly spherical aggregates of graphite, leaving a matrix of ferrite or pearlite according to the exact heat treatment used.

Three basic types of malleable iron are recognized within the casting industry: blackheart, whiteheart, and pearlitic.^[1]