Find the weight percent of austenite present in the steel, Mechanical Engineering

Find the weight percent of austenite present in the steel:

A 0.4% C hypoeutectoid plain carbon steel is slowly cooled from 1540oC to

(i) slightly above 723oC and (ii) slightly below 723oC.

Calculate the weight percent

1.      austenite present in the steel,

2.      ferrite present in the steel in case (i),

3.      proeutectoid ferrite prevent in the steel, and

4.      eutectoid ferrite and eutectoid cementite % present in the steel in case (ii).


Refer to Figure 8. Point 1 above the liquidus represents the state of liquid steel. The cooling occurs along the line xx and an equilibrium cooling is assumed. Freezing begins at point 2 which is intersection of liquidus and line xx. Temperature at 2 is 1510oC. The steel solidifies completely at point 3 where temperature is 1471oC. Now the entire alloy is composed of austenite (γ-phase) as indicated by first of Figure 19. No change occurs until point 4 on line A3 is reached. At this point the precipitation of ferrite begins out of solid austenite. Further cooling increases the amount of ferrite and austenite decreases. The amount of austenite varies along with IK. The composition of the ferrite varies along with the line IL.

Calculation of % content will be made by lever rule.

The amount of austenite slightly above 723oC is calculated from the line LK itself. i.e. taking LK as tie line.

 (a)       Weight % of austenite =   L5/ LK= ( 0.4 - 0.0250)/(0.8 - 0.025)

                                                       =  0.375/0.775  = 0.484 or 48.4%         ---------- (i)

                     Weight % of ferrite    = 5K / LK       =     0.8 - 0.4/0.8 - 0.025

                                                               =     0.4/0.775 = 0.516 or 51.6%        -------- (ii)

 (b)       Weight % of proeutectoid ferrite slightly below 723oC is same as that slightly above, that means 48.4%. ----------- (iii)

For calculating eutectoid ferrite, the weight of carbide will have to be subtracted form total mass of ferrite and cementite. Just below isothermal line LKM ferrite and pearlite are present and lever arm will extend up to ordinate representing 6.67% C.

Weight % of total (ferrite + cementite) just below 723oC

=     6.67 - 0.4/6.67 - 0.025

 =   6.37/6.645

  = 0.96 or 96%

Weight % of Fe3C just below 723oC

=   0.4 - 0.025/6.67 - 0.025

=  0.375/6.645

= 0.0564 or 5.64%      

Weight % of eutectoid cementite = total ferrite - proeutectoid ferrite

                                                              = 96 - 51.6 = 44.4%

Weight % of eutectoid cementite (by difference)

= 100 - 48.4 - 5.64 - 44.4 = 1.56%                                         --------- (iv)

Posted Date: 1/22/2013 1:31:10 AM | Location : United States

Related Discussions:- Find the weight percent of austenite present in the steel, Assignment Help, Ask Question on Find the weight percent of austenite present in the steel, Get Answer, Expert's Help, Find the weight percent of austenite present in the steel Discussions

Write discussion on Find the weight percent of austenite present in the steel
Your posts are moderated
Related Questions
Combined Rules           MOD (modified operation due date)                                 PN j = max (t + o j , t dj ) (SPT-Tr) (Truncated SPT)

Q. Illustrate about Plant Type and Process? Plant layout is influenced by the type of plant (both the industry and technology utilized) and the kind of process units and associ

Calculate force required for equilibrium: A member ABCD is subjected to the point loads P 1 , P 2 , P 3   an d P 4   as shown in the figure given below

Composite Materials While two various materials which neither react chemically nor dissolve in every other are combined together so they form a composite materials. Individual

Which of the following is an open pair?

Orthographic Projections: As you learned previously about the theory of projection of points, planes and lines, the next significant is the projection of solids that have thre

State of CAD Data Exchange: "Are we closely there yet?" the dreaded question we hear wailing from the back of the car. "Yes, nearly there" is our cheerful response. We didn't

give me an example of law of superposition

Define strain: Sol. : STRAIN(e) : When the body is subjected to some external force, there is some change in dimension of body. The ratio between change in the dimension of b

Gathering Lines: A gathering line, also called a ladder track, is one into which a number of parallel tracks merge. This is shown in Figure. It is used in marshalling yards.