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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 ...
Like hot black oxide, mid-temperature black oxide converts the surface of the metal to magnetite (Fe 3 O 4). However, mid-temperature black oxide blackens at a temperature of 90–120 °C (194–248 °F), [6] significantly less than hot black oxide. This is advantageous because it is below the solution's boiling point, meaning there are no ...
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.
Austenite has much higher stacking-fault energy than martensite or pearlite, lowering the wear resistance and increasing the chances of galling, although some or most of the retained austenite can be transformed into martensite by cold and cryogenic treatments prior to tempering.
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.
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 ...
Austenite is slightly undercooled when quenched below Eutectoid temperature. When given more time, stable microconstituents can form: ferrite and cementite. Coarse pearlite is produced when atoms diffuse rapidly after phases that form pearlite nucleate. This transformation is complete at the pearlite finish time (P f).
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 ...