Grain growth, Other Engineering

Q. Explain the grain growth.

Ans. Grain growth: After Recrystallization is complete, the strain free grains will continue to grow if the metal specimen is left at elevated temperature. This phenomenon is called grain growth.

      During grain growth temperature gives atoms of crystal sufficiently mobility to arrange themselves in low energy configuration. Atoms are moves across the interface from small to large grains due to enhance thermal vibration created by temperature.

   The salient features of grain growth are:

(1)   The required energy for grain growth is less than for Recrystallization.

(2)   At Recrystallization temperature grain growth are less although grain growth is depend on temperature.

(3)   Due to grain growth, grains of metals have tendency to come back in more stable state.

(4)   There is maximum size of grain for a particular temperature. After it grain size will not increase even though temperature will rise.

(5)   Fine grains are harder and stronger than coarse grains.

(6)   The appearance of metal surface depends on grain size.

(7)   Grains are abnormally increase if there is no uniform distribution of impurities in metal.

    The factors that control the grain growth of grain size are

(a)   Degree of pre deformation

(b)   Time and temperature of annealing process

(c)    Insoluble impurities present

(a)   Degree of pre deformation: If degree of pre deformation is increases then it produces effective nucleation sites and reduces the final grain size.

(b)   Time and Temperature: Grain growth is the result of increasing temperature above the Recrystallization temperature. Shorter the time of heating to the annealing temperature quick heating finer grain produced. On the other hand slow heating at the annealing process leads to coarse grains.

(c)    Insoluble impurities: Finer impurities with uniform distribution will result in finer grains.

Posted Date: 8/1/2012 9:19:44 AM | Location : United States

Related Discussions:- Grain growth, Assignment Help, Ask Question on Grain growth, Get Answer, Expert's Help, Grain growth Discussions

Write discussion on Grain growth
Your posts are moderated
Related Questions
Inhibit Gate Occasionally it is required to 'hold' one input to an AND gate at a particular logic level in order to disable the entire gate. One method of representing this sy

Q. What are the differences between soldering, brazing and welding? Ans. S.No.  Welding Soldering Brazing

The axial flow compressor: The axial flow compressor is by far the most popular type of compressor and, although it is more difficult to manufacture, it is a more efficient com

How laptop making main function plz established??

Limited travel distances - means of escape: Are travel distances within the maximum allowable distances published in the guidance? Is there good visibility in the

AIRCRAFT RADIO INSTALLATION (STATION) LICENCE AND APPROVAL 1. A radio installation licence is issued by the Department of Trade and Industry Radio Communications Agency , fo

.What is MASM? Explain its features

USE OF MULTICYLINDER ENGINE If, in a multi cylinder engine, power strokes are staggered, the limitation of flywheel can be overcome to a large extent. Torque diagram for 2 cyli

Phase detector Phase detector (PD) consists of a multiplier and a low pass filter. The output of the PD has a magnitude proportional to V s cos 2 φ  where φ is the phase shif

For ramjets, turbojets and turbofans