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Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of ferrite (87.5 wt%) and cementite (12.5 wt%) that occurs in some steels and cast irons. During slow cooling of an iron-carbon alloy, pearlite forms by a eutectoid reaction as austenite cools below 723 °C (1,333 °F) (the eutectoid temperature). Pearlite ...
Time-Temperature-Transformation diagram for two steels: one with 0.4% wt. C (red line) and one with 0.4% wt. C and 2% weight Mn (green line). P = pearlite, B = bainite and M = martensite. Isothermal transformation diagrams (also known as time-temperature-transformation ( TTT ) diagrams ) are plots of temperature versus time (usually on a ...
The red line shows the cooling curve for austempering. 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 ...
Austenite, also known as gamma-phase iron (γ-Fe), is a metallic, non-magnetic allotrope of iron or a solid solution of iron with an alloying element. [1] In plain-carbon steel , austenite exists above the critical eutectoid temperature of 1000 K (727 °C); other alloys of steel have different eutectoid temperatures.
The red line shows the cooling curve for austempering. Austempering is a technique used to form pure bainite, a transitional microstructure found between pearlite and martensite. In normalizing, both upper and lower bainite are usually found mixed with pearlite.
Perlite vs. Vermiculite. Perlite Perlite is a lightweight, granular material made from ground volcanic rock that is usually white in color. It is used to aerate compost and improve soil drainage ...
This requires a temperature drop from around 750 °C (cherry-red) to 450 °C (at which point the transformation is complete) in less than a second to prevent the formation of soft pearlite. Because the rest of the blade cools slowly, the carbon in the austenite has time to precipitate, becoming pearlite.
Seeds can be started in moistened standalone perlite or a 50-50 combination of perlite and soil, which keeps the sprouts from drying out. Perlite vs. Vermiculite Perlite and vermiculite both ...