JJ508 ENGINEERING LABORATORY 3

LAB REPORT

TITLE: METALLOGRAPHIC SPECIMEN PREPARATION

NAME MATRIC NO

ONG MIN XUAN 15DKM13F1005

MUHAMMAD AZRI BIN RUZAIDI 15DKM13F1007

MUHAMMAD HARIS BIN MUKTAAR ALI

15DKM13F1013

MUHAMMAD SYAFIQ BIN MOHAMAD

15DKM13F1021

MUHAMMAD AQIUDDIN BIN ISHAK 15DKM13F1027

LECTURE NAME: PUAN KHAIRUL FAIZAH BINTI SHAHRUDIN

OBJECTIVES: At the end of the session the students will be able to;

1.) Study the methods of metal cutting of specimen.2.) Study the methods to place the specimen for hot mounting.3.) Study the methods of grinding process and polishing process and etching process

of specimen.

Equipment /Apparatus /Component:

1.) Metallographic cutter machine

2.) Mounting Compound

3.) Mounting Press machine

4.) Rotary pregrinder

5.) Polisher

6.) Nital liquid(100ml alcohol and 2ml sulphuric acid)

7.) Specimen to be mounted

8.) Specimen Drier SD6000

9.) Cotton buds,file

SAFETY:

1.) Never Use a metallographic cutter machine and mounting press machine without permission.

2.) Use Glove when handling chemicals

PROCEDURES:

A. HOT MOUNTING1.) First, cut the metal with size not more than 15x15mm using the

Metallographic cutter machine.2.) Secondly, smooth the rough surface of metal with the file.3.) Third, the specimen should be placed with the surface to be examined down.4.) Fourth, spray mounting release on the mould.5.) Fifth, spray mounting release on the mould.6.) Sixth, add ½ scope of the mounting compound (pallet of polymers)into the

mould.7.) Seventh, close the mould tightly and loose up the knob for ½ cycle to open it

up.8.) Next, key in the data in the machine according to type of mounting compound

being used.9.) After that, Press start button and make sure the pressure is levelled at 270 bar

during the heating operation.10.) For a while, once the machine completes its operation , the buzzer will be

on,11.) Next, press again the pressure button, and take out the specimen carefully

from the machine.12.) Lastly, clean the mould and spray mounting release, and then place it back

on the machine.

B. GRINDIN PROCESS1.) First, fit the specimens into the apparatus of the specimen holder.2.) Second, switch on the rotary pre-grinder machine with 240 grit paper.3.) Third, turn on the pipe source on machine.4.) Fourth ,set FWD at 200 rpm5.) Lastly, repeat the same procedures for 360, 600, 800, 1000, 1200 grit papers.

C.POLISHING PROCESS

1.) First, wash the specimen with the warm soapy water followed by alcohol to prevent contamination of the disc.

2.) Second, fit the specimens into the apparatus of the specimen holder for coarser polisher (3 microns.)

3.) Third, use the diamond paste for 3 micron.4.) Fourth, switch on the polisher machine and use diamond lubricator during the

polishing process.5.) Lastly, repeat the same procedures for finer polisher (1micro and diamond

paste for 1 micron.)

D.)ETCHING PROCESS

1.) First, make sure the specimen is clean from any dirt.2.) Second, wash the specimen using Ultrasonic Cleaner and dry it by using

Specimen Drier SD6000 if necessary.3.) Third, the specimen is etched using a reagent.4.) Fourth, etching the specimen by using a regent called as natal.(natal:2ml sulphuric

acid and 100ml alcohol).5.) Next, by using a cotton bud wipe over the surface a few times.6.) Lastly, immediately wash the specimen in alcohol and dry it using Specimen

Drier SD6000.

Result

QUESTIONS:

1) What are the importance of doing Metallographic specimen for examination by microscope?Prepared specimens should be examined with the unaided eye after etching to detect any visible areas that have responded to the etchant differently from the norm as a guide to where microscopical examination should be employed.

2) What type of cutting abrasive used in metallographic cutter? Explain in detail.

Material Composition Recommended Blade

Soft non-ferrous metals (aluminum, brass, zinc, etc.)

Alumina/ resin bonded

MAX-E

Hard non-ferrous metals (titanium, zirconium, etc.)

Silicon carbide / resin-rubber bond

MAX-C

Soft steels Alumina/ resin bonded

MAX-E

Hard and case hardened steels

Alumina/ resin bonded

MAX-HVS

General purpose blade for steels and ferrous metals

Alumina/ resin bonded

MAX-D

Universal thin resin/rubber blade

Alumina / resin-rubber bond

MAX-A

Industrial general purpose thin blade

Alumina / resin-rubber bond

MAX-I

3) Why should mounting, grinding, and etching process done first before conducting an examination by using microscope? Explain in detail.

In this experiment, we using only metallographic techniques, a skilled technician can identify alloys and predict material properties. After mounting, the specimen is wet ground to reveal the surface of the metal. The specimen is successively ground with finer and finer abrasive media. After polishing, certain microstructural constituents can be seen with the microscope, e.g., inclusions and nitrides. If the crystal structure is non-cubic (e.g., a metal with a hexagonal-closed packed crystal structure, such as Ti or Zr) the microstructure can be revealed without etching using crossed polarized light (light microscopy). Otherwise, the microstructural constituents of the specimen are revealed by using a suitable chemical or electrolytic etchant.

4) Why are there sequence steps in grinding and polishing? What will happen if the steps are not followed or ignored

Grinding: After mounting, the specimen is wet ground to reveal the surface of the metal. The specimen is successively ground with finer and finer abrasive media. Silicon carbide abrasive paper was the first method of grinding and is still used today. Many metallographic, however, prefer to use a diamond grit suspension which is dosed onto a reusable fabric pad throughout the polishing process. Diamond grit in suspension might start at 9 micrometer and finish at one micrometer. This process is doing every 5 minutes with different size of grinding paper.

Polishing: Polishing with diamond suspension gives finer results than using silicon carbide papers (SiC papers), especially with revealing porosity, which silicon carbide paper sometimes "smear" over. After grinding the specimen, polishing is performed. Typically, a specimen is polished with a slurry of alumina, silica, or diamond on a napless cloth to produce a scratch-free mirror finish, free from smear, drag, or pull-outs and with minimal deformation remaining from the preparation process. This process will repeat two times every 5 minutes with two different size of polisher paper.

If those two process are not followed or ignored the certain microstructural constituents cannot be seen clearly or cannot see anything the right microstructural with the microscope.

5) Can we conduct the examination of microscope without etching process?

Metallographic etching is the process of revealing microstructural details that would otherwise not be evident on the as-polished sample. Etching is not always required as some features are visible in the as-polished condition such as porosity, cracks and inclusions.

A properly prepared specimen will reveal properties such as grain size, segregation, and the shape, size, and distribution of the phases and inclusions that are present, while other aspects such as mechanical deformation and thermal treatments may also be able to be determined.

CONCLUSION:

First, we saw the microstructure of all types of metallic alloys. It can be more precisely defined as the scientific discipline of observing and determining the chemical and atomic structure and spatial distribution of the constituents, inclusions or phases in metallic alloys. By extension, these same principles can be applied to the characterization of any material.

Different techniques are used to reveal the microstructural features of metals. Most investigations are carried out with incident light microscopy in brightfield mode, but other less common contrasting techniques, like darkfield or differential interference contrast (DIC), and the use of color (tint) etching are expanding the scope of light microscopy for metallographic applications.