Lab03 Metallography

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“In the name of Allah, The Most Beneficent, The Most Merciful”

Lab

#03

Metallography

Prepared BySyarifah Nur Aqida Syed Ahmad [email protected] Ext: Hand phone: Fakulti Kejuruteraan Mekanikal,Universiti Malaysia Pahang

Lab InstructorSyarifah Nur Aqida Syed Ahmad

Lab LocationMaterials Laboratory

Lab Objectives

By the end of semester, students should be able to: sketch and label the constituents of plain carbon steel and cast

iron microstructures at different composition and heat treatment, and

analyze the microstructures of plain carbon steel and cast iron at different composition and heat treatment.

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Date: ____________________

Group Members Student ID Section

2BMM1511 Engineering Mechanics Lab 1_0809/I_document.doc

mailto:[email protected]

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BMM1511 Engineering Mechanics Lab 1_0809/I_document.doc

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1.0 Metallographic Study

Metallography is a technique used to reveal the internal structure of materials. The technique was developed originally for examining internal structure of minerals, metals and alloys, and is still used extensively for that purpose. The technique has been expanded and adapted to look at other materials including composites, and ceramics. The technique involves sectioning a sample to a size suitable for evaluation, grinding to provide a flat surface and for the removal of deformation caused by sectioning, polishing to remove deformation caused by grinding and then etching to reveal internal structure(s) and or feature(s). Etching selectively attacks the constituent parts of the microstructure, causing them to appear separately under the microscope due to differences in the chemical and physical conditions of the constituents.

The crystalline microstructure of metals can be studied by examining it under a microscope at magnifications from 100 to 1000 times. The shape and size of the crystals indicates the composition, work hardening, and heat treatment a metal has received.

In a cold worked specimen, the specimen to be examined should be removed parallel to the direction of the cold work. In a heat treated specimen, the sample should include a portion of the outer skin, so that surface conditions like scale and decarburization can be examined.

Steel, in the annealed condition, consists of pearlite with ferrite or cementite, depending on the carbon content. The carbon content may be estimated by observing the amount of pearlite present.

2.0 Experiment Setup

Before getting started, you should recognize the objective lenses and eyepieces used for the metallurgical microscope and make sure to handle and install them properly.

Equipment and Materials

Metallurgical microscope 5 standard sample of plain carbon steel and cast iron (sample no

2, 3, 4, 12 and 14)


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3.0 Experiment Procedure1. Observe and sketch each microstructure at 100X-400X

magnification. Label the constituents (ferrite, pearlite, grain boundaries, graphite, inclusions, etc.) and describe the important features of the microstructure.

Sample no. 2 : Low carbon steel

Description: _____________________________________________________

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Sample no. 3 : Medium carbon steel (annealing)


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Description: _____________________________________________________

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Sample no. 4 : Medium carbon steel (normalizing)

Description: _____________________________________________________

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Sample no. 12 : White cast iron

Description: _____________________________________________________

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Sample no. 14 : Ductile cast iron

Description: _____________________________________________________

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2. What type of microscope did you use to view your samples (include manufacturer)?

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3. What light source(s) were used to view your samples in the microscope? Were there any special precautions taken/needed to view samples using the light source(s)?

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4. What power objective lenses (and their NA) were available to you to use on your microscope? What power were the eye pieces on your microscope?

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5. What magnification(s) provided you with the best general overall image of your samples?

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4.0 Conclusion

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5.0 Reference

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Lab03 Metallography

Documents

Transcript of Lab03 Metallography