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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).
[2] [3] Acicular ferrite is a fine Widmanstätten constituent, which is nucleated by an optimum intragranular dispersion of oxide/sulfide/silicate particles. The interlocking nature of acicular ferrite, together with its fine grain size (0.5 to 5 μm with aspect ratio from 3:1 to 10:1), provides maximum resistance to crack propagation by cleavage.
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) systems. Such conditions force phases of different composition to form but allow little time for diffusion to produce those phases' equilibrium ...
Under a light microscope, the microstructure of bainite appears darker than untempered martensite because the bainite has more substructure. [9] The hardness of bainite can be between that of pearlite and untempered martensite in the same steel hardness. The fact that it can be produced during both isothermal or continuous cooling is a big ...
Molar volume vs. pressure for α-Fe at room temperature. The primary phase of low-carbon or mild steel and most cast irons at room temperature is ferromagnetic α-Fe. [8] [9] It has a hardness of approximately 80 Brinell. [10] [11] The maximum solubility of carbon is about 0.02 wt% at 727 °C (1,341 °F) and 0.001% at 0 °C (32 °F). [12]
It looks like Aurora Borealis shooting over a mountain range, but it's not.. This is a photograph of a gemstone taken under a microscope. If you're thinking, "I could look at these breath taking ...
As a result of the transformation, the microconstituents, pearlite and bainite, form; pearlite forms at higher temperatures and bainite at lower. TTT diagram of isothermal transformations of a hypoeutectoid carbon steel; showing the main components obtained when cooling the steel and its relation with the Fe-C phase diagram of carbon steels.
Stevie Mitchell scored 17 points and No. 15 Marquette capitalized on an early 21-0 run to defeat a pesky Central Michigan team 70-62 on Monday night. Kam Jones and Chase Ross each added 12 points ...