Malleable

Malleable describes a material's ability to deform under compressive stress without cracking or fracturing. In metals, malleability is typically demonstrated by hammering, rolling, or pressing the material into shapes. The term is often contrasted with brittleness and with ductility; ductility refers to deforming under tensile stress, while malleability emphasizes deformation under compression and forming processes.

Factors influencing malleability include temperature, composition, grain structure, and impurities. At higher temperatures, many metals become more malleable because dislocations move more easily. Cold working can reduce malleability through work hardening. Alloying elements such as carbon in iron or silicon, magnesium, and copper in aluminum can increase or decrease malleability depending on the resulting phase structure and grain size.

Common examples of highly malleable metals are gold, silver, copper, and aluminum, which can be formed into thin sheets or complex shapes. Malleable iron is a class of cast iron that has been heat-treated to become more ductile and formable. Some brass and bronze alloys also exhibit notable malleability under forming processes.

Applications of malleability include sheet metal forming, stamping, coin production, jewelry making, and various components that require shaping through hammering or rolling. Malleability is balanced with other material properties such as strength, hardness, and fatigue resistance to suit specific engineering needs.

Limitations arise from the trade-offs involved: excessive cold work can reduce malleability through hardening, and some materials are inherently brittle and do not exhibit malleability. Understanding malleability helps in selecting materials and controlling processing conditions for shaping operations.