WORK PROCEDURE.
1.
After adjusting the illumination using the aperture and light filters of the
microscope, the necessary magnification is selected.
2.
The samples to be examined are placed one by one on the object table of the
microscope as shown in the previous laboratory work and observed under the
microscope.
3.
Using an atlas of microstructures, the steel structural elements under
investigation are carefully viewed from the photographs. The steady state
microstructures of the steel samples are then viewed and studied at 200 to 500 times
magnification.
4.
Each microstructure viewed under the microscope is drawn on a paper with
a diameter of 50 mm or a square paper with a size of 60x60 mm.
6 – Laboratory work
REPORT
1
. Purpose of work.
2. Necessary equipment and measuring instruments.
3 . Summary of the work done.
Control questions.
1. What is a state diagram?
2. What is eutectic?
3. What is the melting point of metals?
4. What is Ferrite - Perlite.
5. What is austenite, cementite.
6. What is Ledeburit.
153
Laboratory work -7
Topic: Cast iron microstructure analysis.
The purpose of the work:
to study the microstructure analysis of cast iron
Necessary tools and materials:
1. Metallographic microscope.
2. Cast iron samples with different composition.
3. Circle and ruler.
4. Atlas of microstructures of metals and alloys
Theoretical information
Depending on the state of carbon in the cast iron, it is divided into white gray,
very fine, malleable cast iron.
White cast iron contains carbon in the form of cementite. Gray, very fine, malleable
cast iron contains a large part of the carbon rod in the free state, that is, in the form
of graphite.
White cast irons are divided into types according to their structure and carbon
content:
a) Pre-eutectic cast irons (2.14-4.3%S), their structures consist of pearlite,
secondary cementite and ledeburite (Fig. 1, a).
b) Eutectic cast iron (4.3%S), its structure consists only of ledeburite (Fig. 1,
b).
c) Post-eutectic cast irons (4.3-6.67% S), their structures consist of primary
cementite and ledeburite (Fig. 1, c).
Gray cast irons are also called ductile irons because of their high moldability.
Gray cast iron is divided into the following types according to the structure of the
metal base:
|
