A material of unknown composition at atmospheric pressure (arbitrarily chosen) exhibit four phase at 987 K, what is the minimum number of components in the system?
Modified form of phase rule, F = C - P + 1
The minimum number of components correspond . - to minimum degrees of freedom, which is zero
∴ 0 = C - 4 + 1 or C = 3
The percentage of pro-eutectoid ferrite and pearlite in a slowly cooled 0.5% carbon steel is
Let fulcrum is at 0.5% carbon to apply lever rule. % Proeutectoid ferrite
% Pearlite = 100 - 37.5 = 62.5%
Microstructure of pearlite is composed of X% ferrite and Y% cementite. The value of X and Y is
In which of the following phases'of steel cementite is in particle form?
Bainite: When austenite is cooled rapidly past the nose of C-curve and kept isothermally in a constant temperature bath, it transforms to a nonlamellar product known as bainite. It is an extremely fine mixture of ferrite and carbide. Bainite is present in two forms: the feathery bainite obtained in the upper part of temperature range and needie-like or accicular bainite produced by lower reaction temperature.
In which of the following phases of steel, cementite is in lamellar form?
Pearlite phase in steel is made up of alternate layers of ferrite and cementite.
The maximum number of co-existing phases in a C- system is
Hardness of martensite is about
0.2% C Martensite →50 RC
0.4% C Martensite →58 RC
0.8% C Martensite→ 65 RC
Hardness of steel depends
Increasing the carbon content in steel alloys causes the material to become harder. This is because the carbon sits in the interstitial sites of the lattice structure and hinders the movement of dislocation lines. It also increases the strength of the material but it decreases the ductility, carbide is hard phase,
The reaction that on heating one solid phase yields another solid phase together with one liquid phase is termed
Eutectic product in Fe-C system is called
A eutectic reaction occurs at 1146°C
On cooling through the eutectic temperature, the lowest melting liquid of the system decomposes to solid phases, austenite and cementite. This eutectic mixture is knonw as ledeburite.