cementite

Crucible steel is typified by cementite spheroids, which often stretch into rods during forging as they are deformed.

If you dissolve cementite in acid, removing the iron component, you are left with carbon.

I would like to know what volume fraction of CNTs and cementite (Fe3C) nanowires were present.

Pearlite, which you mention, consists of two phases, cementite and ferrite.

Furthermore, some evidence points that true Damascus Steel had carbon nanotubes and cementite nanowires strengthening the blade (possibly created through the unknown ancient forging process).

Martensite forms by rapidly cooling austenite without giving the atoms the ability to re-organize into their preferred structure (ferrite, pearlite, or cementite depending on the carbon concentration).

> This does not mean there was an intact carbon nanotube in the core of the cementite rod - and even if it DID mean that, it would have negligible impact on performance because it is *encased* in cementite, which itself is in a soft matrix of pearlite or sorbite.

Reibold et al's analyses spoke of the presence of carbon nanotubes enclosing nanowires of cementite, with the trace elements/impurities of vanadium, molybdenum, chromium etc contributing to their creation, in cycles of heating/cooling/forging.

Ferrite and cementite can form nanolaminated microstructures called pearlite and bainite which have a major influence on the properties of the steel, and there are other microstructures that form depending on cooling speed, heat treatment, and cold working.

There are four major phases that play roles even in the commonest carbon steel (ferrite, cementite, austenite, and martensite), plus others that can form at times like graphite, which plays an important role in cast irons.

These cooling rates are only able to be achieved a little ways into the bulk of the material, so you usually end up with a hardened case made of martensite, and a softer more ductile core that is usually pearlite (layers of ferrite [pure iron] and cementite [iron carbide]) that form due to the slower cooling in the core.

This one is hardened to RC-57 (soft for the genre), ground from a hot-forged steel with 1.03%, carbon, 13.06% chromium, 0.37% nickel, and 0.28% nicklel, heated to 1000 degrees to promote austenization, and then oil quenched to form a highly martensitic steel, with moderate levels of pearlite and low levels of cementite.

Less cementite aka iron carbide aka the stuff that actually makes steel "steel" instead of plain iron.

Here's a list of some of the various grains in steel: Pearlite, Cementite, Bainite, Austenite (there are many more).

Martensite, Ferrite Austenite, Cementite, etc.