1. Exp.1: Preparation of Specimens for Metallographic Examination
Eng. Ahmed Al-Afeefy
Eng. Ahmed Y. Manama

2. Objective
To learn and gain experience in the preparation of metallographic specimens.
To examine and analyze the microstructures of metals and metallic alloys.

3. Introduction
Metallography is basically the study of the structures and constitution of metals and alloys, using metallurgical microscopes and magnifications, so that the physical and mechanical properties of an alloy can be related to its observed microstructure.

4. Introduction
Such microscopic studies can provide constitutional information about the specimen under investigation, including:
The size and shape of the grains,
The presence of micro defects,
The nature and distribution of secondary phases.

5. Introduction
Proper preparation of metallographic specimens to determine microstructure and content requires that a rigid step-by-step process be followed. In sequence, the steps include:
Sectioning (cutting),
Mounting,
Grinding,
Polishing,
Etching ,
Microscopic examination.

6. Procedures Sectioning (cutting):
The preparation starts by cutting a small representative piece of the metal to be studied. Cutting can change the microstructure of a sample.
Minitom

7. Procedures
Cleaning
Specimens must be kept clean in order to reveal accurate microstructures.
Metason

8. Procedures
Mounting
Small samples are generally mounted in plastic for convenience in handling and to protect the edges of the specimen being prepared.
LaboPress-3

9. Hot Mounting Cylinder dia. Resin heating Cooling 30 mm Type Time Temp.
Force
Rate
[min]
[oC]
[kN]
PolyFast
4-6
180 20
2-3
HIGH
MultiFast (block)

10. Optimizing the amount of resin
It is important to supply enough resin during mounting. If the amount of resin is too small to cover the specimen after curing, the specimen, and the cylinder may all be damaged.
Min no. of Spoons =
Height of 1 Spoon (15 mm) of Resin after Mounting in an Empty Cylinder
Cylinder dia:
30 mm
Resin: mm
inch
PolyFast
11.3
0.44
MultiFast (black)
8.9
0.35

11. Procedures
Grinding
The entire process is designed to produce a scratch free surface by employing a series of successively finer abrasives.
Rotating Discs

12. Grinding Surface MD-Primo 220 MD-Largo Abrasive SiC DP-Suspension
Grit / Grain size -
9µm
Lubricant
Water
Green/Blue
rpm
300
150
Force(N)
120
180
Time (min)
Until Plane 5

13. Procedures
Polishing
To remove deformations from grinding and obtain a surface that is highly reflective.
(rotating discs covered with soft cloth )
Rotating Discs

14. Polishing Surface Abrasive Grit / Grain size Lubricant rpm Force(N)
MD-Dac
MD-Nap or MD-Chem
Abrasive
DP-Suspension
OP-S or OP-U
Grit / Grain size
3µm -
Lubricant
Green/Blue
rpm
150
Force(N)
190 60
Time (min) 5

15. Procedures
Etching
Etching occurs when the acid or base is placed on the specimen surface. The purpose of etching:
Grinding and polishing operations produce a highly deformed, thin layer on the surface which is removed chemically during etching.
Etching is used to highlight, and sometimes identify, microstructural features or phases present.
LectroPol-5:

16. Procedures
Microscopic examination
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