Metallurgy Terms: Blowholes, Hardenability, and More
Metallurgy Terms
Blowholes
Blowholes are cavities formed when gases dissolved in an alloy are trapped during solidification.
Hardenability
Hardenability is the ability of a material to be tempered.
Carburetion
Carburetion is the process of combining carbon and iron to make steel.
Esteadite
Esteadite is a type of eutectic melting, hard and brittle, with a melting temperature of 960°C. In foundries, it appears gray.
Diffusion
Diffusion is the movement of atoms in a disordered lattice from their equilibrium position to a nearby one.
Anisotropy
Anisotropy is the general property of matter where certain physical properties, such as elasticity, temperature, conductivity, and the velocity of light propagation, vary depending on the direction being examined.
Annealing (Supercritical)
Supercritical annealing occurs when steel is heated to temperatures above the critical point, increasing the tendency to fatigue.
Fatigue
Fatigue is the fracture of a material under loads below its fracture strength, which occurs over a certain period of time.
Martempering
Martempering is a procedure that involves heating steel to its austenitizing temperature and then rapidly cooling it in a salt bath or hot oil to a temperature slightly above Ms (martensite start temperature). This temperature is held constant to standardize the temperature of the piece (the isothermal treatment is stopped before the start of bainitic transformation), then cooled to produce 100% martensite. This treatment reduces the risk of distortion and fractures.
Recrystallization
Recrystallization is a heat treatment process where a cold-worked metal is heated to a temperature high enough for a sufficient time interval to form a new grain structure free of distortion. Through this process, atoms, ions, or molecules are rearranged to form the crystal lattice, greatly reducing the metal’s dislocation density.
Ledeburite Composition at Eutectic Point
Ledeburite’s composition at the eutectic point is 4.3% austenite + cementite.
Chemical Affinity
Chemical affinity, A, is the energy exchanged when a neutral atom X in the gaseous state and in its ground electronic state receives an electron and becomes a mononegative ion X–, also in the gaseous state and in its ground electronic state.
Dendrites
If a pure metal is cooled uniformly, reaching the solidification temperature, germ nuclei arise. These nuclei develop in the direction of certain crystal axes, giving rise to arborescent forms called dendrites.
Grain Refinement
Grain refinement is a transformation that occurs in steels, generally through annealing, to achieve a smaller grain size and, consequently, improved metal features.
Composite Materials
Composite materials, also called hybrids, are a set of technical source materials and designs resulting from integrating two or more different materials into another with different properties than each material possesses separately.
Alpha and Beta Particles
Alpha particles appear in the decay of radioactive substances and are equivalent to the helium atom with two positive charges (the helium nucleus), while beta particles are identical to electrons.
Valence
Valence indicates the number of electrons in the last layer of an element that are responsible for bonding.