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The concept of microstructure is observable in macrostructural features in commonplace objects. Galvanized steel, such as the casing of a lamp post or road divider, exhibits a non-uniformly colored patchwork of interlocking polygons of different shades of grey or silver.
Dissimilar friction stir welding (DFSW) is the application of friction stir welding (FSW), invented in The Welding Institute (TWI) in 1991, [1] to join different base metals including aluminum, copper, steel, titanium, magnesium and other materials. [2]
Austempering is heat treatment that is applied to ferrous metals, most notably steel and ductile iron. In steel it produces a bainite microstructure whereas in cast irons it produces a structure of acicular ferrite and high carbon, stabilized austenite known as ausferrite. It is primarily used to improve mechanical properties or reduce ...
The properties of steel depend on its microstructure: the arrangement of different phases, some harder, some with greater ductility. At the atomic level, the four phases of auto steel include martensite (the hardest yet most brittle), bainite (less hard), ferrite (more ductile), and austenite (the most ductile). The phases are arranged by ...
In materials science, lamellar structures or microstructures are composed of fine, alternating layers of different materials in the form of lamellae. They are often observed in cases where a phase transition front moves quickly, leaving behind two solid products, as in rapid cooling of eutectic (such as solder ) or eutectoid (such as pearlite ...
For a eutectoid steel (0.76% C), between 6 and 10% of austenite, called retained austenite, will remain. The percentage of retained austenite increases from insignificant for less than 0.6% C steel, to 13% retained austenite at 0.95% C and 30–47% retained austenite for a 1.4% carbon steel. A very rapid quench is essential to create martensite.
This microstructure is advantageous over other microstructures for steel because of its chaotic ordering, which increases toughness. [ 1 ] Acicular ferrite is formed in the interior of the original austenitic grains by direct nucleation on the inclusions, resulting in randomly oriented short ferrite needles with a 'basket weave' appearance.
Bainite is a plate-like microstructure that forms in steels at temperatures of 125–550 °C (depending on alloy content). [1] First described by E. S. Davenport and Edgar Bain, [2] [3] it is one of the products that may form when austenite (the face-centered cubic crystal structure of iron) is cooled past a temperature where it is no longer thermodynamically stable with respect to ferrite ...