What is Nano bainite?
An alloy system based on iron is described in which it has been possible to create a high density of interfaces by heat-treatment alone. The resulting structure consists of a mixture of slender platelets of bainitic ferrite, just 20-40 nm in thickness, embedded in a matrix of carbon-enriched austenite.
What is the microstructure of lower bainite?
The general definition of bainite is that the microstructure consists of a non-lamellar mixture of ferrite and carbides. Lower bainite consists of fine needlelike plates or laths with the carbides precipitated within the laths.
What are the properties of pearlite?
Pearlite can be hard and strong but is not particularly tough. It can be wear-resistant because of a strong lamellar network of ferrite and cementite. Examples of applications include cutting tools, high strength wires, knives, chisels, and nails.
What is bainite and martensite?
Bainite is a type of steel that’s produced by cooling faster than pearlite but slower than martensite. Additionally, bainite has plate-shaped designs in its microstructures, while martensite has long oval-shaped designs. Without tempering, martensite is simply too hard, making it susceptible to breakage upon impact.
What are the mechanical properties of bainite?
A yield strength as high as 1.5 GPa and an ultimate tensile strength between 1.77 to 2.2 GPa has been achieved, depending on the transformation temperature. Furthermore, the high strength is frequently accompanied by ductility (about 30%) and respectable levels of fracture toughness (about 45 MPa m0.5).
Which is harder pearlite or bainite?
The lower strength of bainite at its highest formation temperature indicates that it is a coarser structure than pearlite at its lowest formation temperature; in the range of mixed structures the bainite may be the coarser of the two structures present.
What kind of structure does a bainite have?
Some of the plates of bainite are incredibly long and thin (20–40 nm), giving an ultrafine scale structure consisting of an intimate mixture of austenite and ferrite. Dislocation debris is evident in both the bainitic ferrite and the surrounding austenite.
How does bainite in steels form at temperature?
Bainite in Steels Bainite forms by the decomposition of austenite at a temperature which is above M Sbut below that at which fine pearlite forms. All bainite forms below the T 0temperature. All time–temperature–transformation (TTT) diagrams consist essentially of two C–curves (Fig. 1).
How is the bainite transformation different from the pearlite transformation?
The pearlite transformation involves the redistribution of carbon followed by a structure change, the martensite transformation involves the structure change alone, and, in contrast, the bainite transformation involves a structure change followed by the redistribution of carbon, which precipitates as a carbide.
What is the difference between bainite and martensite?
Bainite ordinarily refers to the ferrite-carbide aggregates that form in an intermediate temperature range overlapped by pearlite transformation and proeutectoid ferrite or cementite precipitation at higher temperatures and martensite transformation at lower temperatures.