Understanding Steel Transformations, Alloys, and Defects
Steel Transformations and Properties
Annealing and Grain Size
Annealing is a crucial process in steel transformation, generally employed to achieve a smaller grain size. This, in turn, lowers metal features. Anisotropy is a general property where physical properties like elasticity, temperature, conductivity, and velocity of spreading light vary depending on the direction in which they are examined.
Alloys and Overheated Steel
An alloy is a system consisting of several elements, with at least one being a metal at room temperature, retaining metallic properties. Overheated steel occurs when heat treatment temperature or heating time is excessive, producing a large grain size.
Effervescent and Calmed Steels
Effervescent steels have only a small fraction of oxygen removed during solidification, leaving an outer layer or rim relatively free of carbon. This means the center of the ingot has a higher carbon content than the outside. This surface, with an extremely low carbon portion, is very ductile, possesses excellent surface characteristics, and is very good for cold forming.
Calmed steels are the opposite of effervescent steels. These steels have had a large amount of oxygen extracted, resulting in a steel relatively free of carbon. Calmed steels are useful when you need serious shaping techniques but always require heat treatment to complete the manufacturing technique of forming.
Steel Composition
Steel is an alloy of iron and carbon, where carbon does not exceed 2.1% by weight of the alloy composition, normally reaching rates between 0.2% and 0.3%.
Pig Iron
Pig iron is the first foundry steel product obtained in the blast furnace from iron ores.
Chemical Affinity
Chemical affinity, or electron affinity (A), is the energy exchanged in the process by which a neutral atom X, in a 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 electronic ground state.
Bainite
Bainite is a mixture of ferrite and cementite obtained from the isothermal transformation of austenite, starting with the formation of ferrite.
Bronze
Bronze is the name given to a number of metal alloys which are based on copper combined with 3 to 20% of tin.
Composites
Composites, also called hybrid materials, are a set of original materials and design techniques primarily resulting from integrating 2 or more different materials with different properties. Each material separately contributes unique characteristics.
Grain Growth
Granular growth occurs when, at the end of recrystallization, heating is continued above the recrystallization temperature, and another stage begins where the grain structure continues to grow with increasing temperature.
Steel Product Rating
Rating of steel products according to UNE includes iron, steel, thermo-alloys, and special alloys.
Carburation
Carburation is the act of combining carbon and iron to make steel.
Grain Growth and Cooling
When the crystallization process ends, the grain size is large. However, if we keep increasing the temperature above the recrystallization temperature, grain growth starts.
Frenkel and Schottky Defects
Frenkel defect is the combination of an interstitial atom and the hole it has left after the jump. Schottky Effect: Strengthening the thermionic emission of a conductor as a result of an electric field at the conductor surface.
Dislocation
A dislocation is a line defect consisting of a local disturbance of the lattice. Types include edge, screw, and mixed dislocations.