Microstructure Analysis Edited

7/23/2019 Microstructure Analysis Edited

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INTRODUCTION

Microstructure analysis is an art and science of preparing,interpreting and

analyzing microstructure in real engineering material applications to

understand and study the behavior,the grain structure of the materials and

its performance.Meanwhile,metallurgy is the of microstructural features ofmaterials.Metallography involved three main steps in order conduct the

microscopic analysis of the material.The steps which is grinding,polishing

and etching is involved in this experiment.

Grinding

Grinding is required to ensure the specimen surface is at and parallel to

reduce the damage produced during sectioning.This process accomplished

by using four dierent grit of sand paper to get the desired smoothness.

Polishing

!fter grinding,the specimen will be polished using the polishing device where

the diamond particles and lubricants is used during this process.The

polishing is using "micrometer as rough polishing and #micrometer as $nal

polishing until the specimen have mirror surface.

Etching

%thcing is the process where the specimen is immersed into chemical

solution for a while.%tching is important to ma&e the microstructure of thematerial clearer.

OBJECTIVE:

• To be familiar with metallography techniques such as grinding,polishing

and etching.

• To be familiar with metallurgy microscope.

• To investigate the microstructure of metal.



DATA AND OBSERVATIONS

'ample ( Mild 'teel

'ilicon )arbide paper ( *+ grit

( #- grit

( grit

( / grit

0iamond paste ( " micron and * micron

!lcohol solution ( !cetone

%tching solution ( 1ydrochloric acid 21)l3

Microscope lens ( '.plan M, ."/ in$nity4

!fter grinding ( 'urface of the sample became at, parallel

and smoother.

!fter polishing ( " micron 5 the surface of the sample became

shine and mirror.

( * micron 5 the surface became even shinier and

more mirrorli&e.

!fter etching 2-6# seconds3 (The surface become dull and rough.

!fter etching2# and above3 (The surface more dull and rougher.



ANALYSIS AND RESULTS

7igure *.!fter 8olishing !nd 9efore %tching



7igure -.!fter %tching -6# seconds.

7igure #.!fter %tching # seconds.



!ccording to the $gure *,we can see that the surface is not uniformly

at.This is due to the damaged created during grinding section.!fter etching

-6# second,grain boundries can be seen clearer and become dull27igure

-3.7igure # shows that the surface become more dull.

DISCUSSION

Metallography is the study of microstructural features of materials.The

structure studied by metallography are indicative of the properties and

hence the performance of material in service.This process is also to chec&

the eectiveness of heat treatment such as annealing.Metal specimens is

commonly being grinded,polished and etched with 1ydrochloric solution.The

etching process is used to bring out the grain structure so that when

analysed under microscope,the grain structure can be seen clearly.

The metallography involved three main steps which is grinding,polishing andetching.The specimen will be grinded with four dierent 'ilicon carbide paper

starting with the coarsest and the smoothest to ensure the surface is at and

smooth.

Then,the specimen is polished with "micron diamond as the rough polishing

and #micron for the $nal $nishing.The result,the specimen will become

shinier and mirrorli&e surface.

:ext,the specimen was etched using chemical solution.The specimen

immersed into solution for -6#second to bring out the grain structure.7or

second etching,the metal immersed for more than # second and the metal

was observed under microscope to observe the metal structure.The etching

by more than # seconds can change the metal properties.

;ast but not least,the specimen was observed under microscope.7or the

$rst,after polishing before etching,the structure is at and smooth.!fter

etching -6# second,the grain structure and boundries become clearer.!fter

etching more than # second,the microstructure become dar&er and the grain

structure become smaller and smaller.

!nnealing and quenching are some examples of heat treatments. !nnealing

involves heating the metal to a speci$c temp and &eeping it there for a time

before allowing it to cool. <uenching involves heating a metal to a particular

temp and then cooling it suddenly in oil or water. These procedure will alter

the crystalline structure of the mild steel and hence its physical

properties.The microstructure is applied in almost real engineering

applications such as welding and structural applications.



CONCLUSIONS

=n this experiment,the principle of microstructure analysis is clearly

understood.The steps of grinding,polishing and etching is carried out and

well understood.1ence after the three steps,the specimen was observed

under microscope.The grain structure is clearly seen also the grainboundries.The main observation of the microstructure of the specimen is

ferrite and pearlite.;ighter area is ferrite and dar&er area is pearlite.

REERENCE

• 'emester - -*/4-*". MEMD221 Materials Laboratory Manual. )>%,

?niten. pp "*6".

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Microstructure Analysis Edited