How to distinguish one time, two time, three dimensional cementite

The differences between primary, secondary and tertiary cementite methods are:

1. Distinguish from the precipitation place: primary cementite is directly precipitated from the liquid phase; Secondary cementite is precipitated from austenite; Tertiary cementite is precipitated from ferrite.

2. From the morphology: the primary cementite presents a regular long strip; Secondary cementite is generally reticulated; Tertiary cementite is generally reticulated or intermittently reticulated.

Primary cementite is precipitated directly from the liquid phase.

Secondary cementite is precipitated from austenite;

Tertiary cementite is precipitated from ferrite.

Organizationally, primary cementite can only be seen in iron-carbon alloys (white iron) with a greater carbon content.

Its morphology can be large slats (in eutectic white iron). In addition, the cementite contained in the high-temperature Laideonime can also be counted as primary cementite, as they are also precipitated from the liquid phase by eutectic reaction.

The most typical secondary cementites are those distributed along the grain boundary network in the annealed equilibrium structure of pereutectic steels.

In addition, the cementite flakes contained in the pearlite can also be counted as secondary cementite, as they are also precipitated by eutectic reactions in the austenite.

Then there is the cementite that precipitates from the austenite block as the temperature decreases when the subeutectic white iron is cooled.

When eutectic and eutectic white iron are cooled, cementite is precipitated from the austenite contained in high-temperature Laistenite, which is also a secondary cementite.

These can be considered as secondary cementite, but they are generally not clearly indicated (especially Laisterite, which is a more complex mixture, including primary cementite and secondary cementite).

Tertiary cementite is difficult to observe because the amount is too small, usually those small dots in the ferrite area.

I'll give you a **, there's a picture on it.

Summary. The carbon content of secondary cementite is generally in between, depending on the type, size and structure of cementite.

The carbon content of secondary cementite is generally in between, depending on the type, size and structure of cementite.

Can you tell us more about that?

The amount of carbon bench in the secondary cementite depends on the type, size and structure of the cementite. The type of cementite can be carbon fiber, carbon fiber reinforced plastic (CFRP), carbon fiber reinforced resin (CFR), or carbon fiber reinforced glass (CFRG), etc. The size and digging of the carburized jujube body can be fiber diameter, fiber length, fiber density, etc.

The structure of cementite can be a single-layer structure, a multi-layer structure, or a composite structure, etc.