What is the microstructure of eutectoid steel?

What is the microstructure of eutectoid steel?

The equilibrium microstructure of eutectoid steel obtained at room temperature is pearlite (Fig. 6(c)) which is a mixture of two microconstituents named ferrite (α) and cementite (Fe3C); ferrite is very soft while cementite is a very hard constituent of steel.

What is eutectoid microstructure?

Eutectoid structures are like eutectic structures but much finer in scale. The original solid decomposes into two others, both with compositions which differ from the original, and in the form (usually) of fine, parallel plates.

What are the phases of a eutectoid steel?

Eutectoid steels Note that the microstructure of the steel is always composed of the two phases ferrite and cementite, regardless of whether it is a hypoeutectoid (hypopearlitic) steel or a hypereutectoid (hyperpearlitic) steel. This is precisely the characteristic of the metastable system.

What is the microstructure of steel?

The microstructure is predominantly martensite but also has allotriomorphic ferrite, Widmanstätten ferrite, bainite and pearlite. Notice that the spherical shape of a pearlite colony is obvious in this sample because of the lack of impingment.

What is eutectic and eutectoid?

Eutectoid: Eutectoid refers to a homogeneous solid mixture that forms from cooling two or more melted metals to a certain temperature. Eutectic Temperature or Eutectic Point: The eutectic temperature is the lowest possible melting temperature for all of the mixing ratios of the component substances in a eutectoid.

What are the properties of eutectoid?

Eutectoid steel with fine (α+θ) structure, which consisted of ferrite matrix with the average size of about 4.9 μm and fine cementite particles mainly within ferrite grains, was formed by hot deformation of undercooled austenite to the strain of 1.61 at 650 °C at 5 s−1 followed by water-quenching and subsequent …

What is a eutectoid structure?

In eutectoid reaction, solid austenite transforms to two solid phases forming a lamellar (eutectic) structure. The lamellas are cementite lamellas and α-ferrite lamellas. The eutectic structure will be coarse when the growth is slow and fine after rapid growth.

What is eutectoid phase diagram?

The eutectoid reaction describes the phase transformation of one solid into two different solids. In the Fe-C system, there is a eutectoid point at approximately 0.8wt% C, 723°C. The phase just above the eutectoid temperature for plain carbon steels is known as austenite or gamma.

Which microstructure in eutectoid steel has maximum hardness?

Upon rapid cooling to less than 100° temperatures, martensite will be formed. The hardness increases from Pearlite to martensite that is martensite has the highest hardness.

How many types of microstructure are there in steel?

One is bcc (body centered cubic) and the other is fcc (face centered cubic). The bcc crystalline form (?-iron) is stable until a temperature of 912 deg C when it is transformed to fcc (?-iron). The?-iron remains stable until 1394 deg C, and then it reverts to bcc structure (?-iron).?-

What is meant by eutectoid steels?

Definitions of eutectoid steel. a steel that contains 0.9% carbon (the eutectic point); a carbon steel with 0.9% carbon is pure pearlite. type of: carbon steel. steel whose characteristics are determined by the amount of carbon it contains.

What is eutectoid in phase diagrams?

Eutectoid is used to signify that the liquid phase in a eutectic phase diagram has been replaced by a solid phase. Otherwise the eutectoid and eutectic definitions are identical. For example, in steels the solid gamma phase undergoes a eutectoid reaction to become a lamellar mixture of alpha and cementite.

What is a eutectoid composition?

A mixture of phases whose composition are determined by the eutectoid point in the solid region of an equilibrium diagram and whose constituents are formed by eutectoid reaction.

What is eutectoid system?

What is the strongest steel microstructure?

Martensite
Martensite: the hardest and strongest microstructure, yet the most brittle.