Cane ( reed , frustrates ; named after the French chemist Louis-Joseph Trust fr. LJ Troost)) - the structural component of iron-carbon alloys (cast iron, steel). Troostitis is a highly dispersed perlite . The latter, in turn, is a eutectoid mixture of ferrite and cementite .
| Troostitis |
|---|
| Phases of Iron Carbon Alloys |
Ferrite ( solid solution of intercalation of C in α- iron with a body-centered cubic lattice) |
| Structures of Iron-Carbon Alloys |
Ledeburite ( eutectic mixture of crystals of cementite and austenite, which turns into perlite upon cooling) |
| Become |
Structural steel (up to 0.8% C )
Stainless steel ( chrome alloyed ) |
| Cast iron |
White cast iron (brittle, contains ledeburite and does not contain graphite) |
Troostite is formed as a result of the decomposition of austenite at temperatures below 600 ° C. The transformation of austenite into troostitis occurs by diffusion, the type of troostitis formed depends on the temperature of the transformation. Hardening troostite formed during the decomposition of austenite in the temperature range 400–500 ° C contains lamellar cementite, in contrast to tempering troostite, which is formed during tempering at temperatures of 350–400 ° C and contains granular cementite.
The interplate distance in the hardening troostite does not exceed 0.1 μm . The hardness of troostite is higher than perlite or sorbitol . In an optical microscope, troostitis is observed as dark areas against the background of bright fields of martensite, while it is almost impossible to differentiate the individual components of a ferrite-cementite mixture due to its fineness. However, under the electron microscope, the lamellar structure of troostitis with a fan-shaped arrangement of plates is easily observed.
Perlite, sorbitol and troostite are structures of the same nature (ferrite + cementite) and differing only in the degree of dispersion of these components.
Sources
- Gulyaev A.P., Heat treatment of steel, 2nd ed., M., 1960.
- Bunin K.P., Baranov A.A., Metallography, M., 1970.
- Ivanov V. N. Dictionary dictionary on foundry. - M.: Mechanical Engineering, 1990. - 384 p.: Ill. ISBN 5-217-00241-7 .