cold short
Of metal: brittle at low temperatures.
cold short: metal that cracks when you bend it cold
A metal is cold short when it becomes brittle and fractures easily below a certain temperature, even under modest mechanical stress. The brittleness appears suddenly as temperature drops, not gradually. Steel, cast iron, and some copper alloys exhibit this behavior. A structural beam that bends safely at room temperature might snap like glass at minus 20 degrees Celsius.
Cold shortness usually results from the presence of phosphorus, sulfur, or arsenic in the metal. These elements accumulate at grain boundaries, weakening the bonds between crystals. The effect worsens with higher carbon content and larger grain size. Manganese and nickel additions can suppress cold shortness by counteracting these segregation effects. This is why low-temperature structural steel contains deliberate manganese additions and tight phosphorus limits specified in standards like ASTM A572.
Variants and practical impact
Cold shortness differs from hot shortness (brittleness at high temperature, usually from oxygen or sulfur). A metal can suffer from one, both, or neither. Pipeline steel used in arctic environments must be tested for transition temperature using impact tests like Charpy V-notch, which measures the energy absorbed before fracture across a range of temperatures. Steel with poor cold short resistance will show a sharp drop in absorbed energy below its transition temperature.
The Ductile-Brittle Transition Temperature (DBTT) defines the threshold. Austenitic stainless steels and aluminum alloys typically have DBTT well below normal service conditions. Body-centered cubic metals like ferritic steel and most cast irons have higher DBTT and are prone to cold shortness unless carefully controlled. Design practice accounts for this: arctic pipelines use steel with DBTT below minus 40 degrees Celsius, while temperate applications tolerate higher transition temperatures.
The term "short" reflects the appearance of brittle fracture: the break is short and sudden, with little permanent deformation, rather than the long ductile necking seen in room-temperature failure. It is a materials defect, not a processing fault, though processing can reduce severity by grain refinement and element control.