Red-short, hot-short refers to brittleness of steels at red-hot temperatures. It is often caused by high

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

levels, in which case it is also known as sulfur embrittlement.

Iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

, when heated to above 460 °C (900 °F), glows with a red color. The color of heated iron changes predictably (due to

black-body radiation Black-body radiation is the thermal radiation, thermal electromagnetic radiation within, or surrounding, a body in thermodynamic equilibrium with its environment, emitted by a black body (an idealized opaque, non-reflective body). It has a specific ...

) from dull red through orange and yellow to white, and can be a useful indicator of its temperature. Good quality iron or steel at and above this temperature becomes increasingly

malleable Ductility refers to the ability of a material to sustain significant plastic deformation before fracture. Plastic deformation is the permanent distortion of a material under applied stress, as opposed to elastic deformation, which is reversi ...

and plastic. Red-short iron or steel, on the other hand, becomes crumbly and brittle.

Sulfur hot-shortness

In steel contaminated by sulfur this embrittlement happens due to the sulfur forming iron sulfide/iron mixtures in the grain boundaries of the metal which have a lower melting point than the steel.Deev et al. (May–June 1982)
"Role of iron sulfide in the formation of cracks in weld joints"
''Materials Science'', Vol. 18, No. 3, pp. 109–112. When the steel is heated up and worked, the mechanical energy added to the workpiece increases the temperature further. The

iron sulfide Iron sulfide or iron sulphide can refer to range of chemical compounds composed of iron and sulfur. Minerals By increasing order of stability: * Iron(II) sulfide, FeS * Greigite, Fe3S4 (cubic) * Pyrrhotite, Fe1−xS (where x = 0 to 0.2) (monocli ...

(FeS) or iron/iron sulfide alloy (which has an even lower melting point)Sachinath Mitra.
High-pressure geochemistry and mineral physics
'. p. 1028. begins to melt, and the steel starts to separate at the grain boundaries. Steelmakers add

manganese Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...

(Mn) to the steel when it is produced, to form manganese sulfide (MnS). Manganese sulfide inclusions have a higher melting point and do not concentrate at the grain boundaries. Thus, when the steel is later heated up and worked, the melting at the grain boundaries does not occur.

Copper hot-shortness

When steel has elevated levels of copper, which may happen due to ore specifics but is more often cased by contamination of steel

scrap Scrap consists of recyclable materials, usually metals, left over from product manufacturing and consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap can have monetary value, especially recover ...

, also exhibits hot-shortness. This is caused by selective oxidation of iron at the grain boundaries, where more noble and softer copper is enriched.

References

Metallurgy {{industry-stub