determination of hardness of titanium samplehome.iitk.ac.in/~priyansh/p3.pdf · introduction...
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DETERMINATION OFHARDNESS OF TITANIUM SAMPLE
Priyanshu 12518 Raghvendra 12528Proneet 12520 Rahul 12535Punkesh 12522 Ashutosh 12542
Tuesday Group 22014
Dept. of Materials Science & Engineering
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Outline
Background: Introduction to indentation techniques
Objective: Determination of mechanical properties of titanium using Vickers
Micro Indenter
Work done: Polishing, etching, Indentation
Instruments: Metallographic polishing machine., Vicker’s Microindenter
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Introduction
Hardness: Measure of material’s resistance to permanent deformation
Indentation : Technique for measuring hardness of a material
Some major indentation techniques: Brinell Hardness Test, Rockwell Hardness Test, Vickers Hardness Test
HR=E - e
Brinell
Rockwell
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Vickers Hardness test
The Vickers hardness test consists of indenting the test material with a diamond indenter, in the form of a right pyramid with a square base and at an angle of 136 degrees between opposite faces subjected to a load.
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Why?
• It is based on an optical measurement system.
• Indentation made is very small hence, it can be used for very thin foils, tiny surfaces, and small samples.
• It works for a large scale of hardness scale and does not destroy the specimen
• Accurate results for homogeneous materials
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ProcedureSample preparation
Polishing:
• Silicon Carbide Abrasive strips (1/0, 2/0, 3/0)
• Metallographic polishing machine (Grit size: P320,P800,P1000,P1200,P2500)
• Cloth polishing (Semi finer liquid, finer liquid)
Etching:
with Kroll’s reagent
• Distilled Water(90 ml)
• HNO3 (8ml)
• HF (2ml)
Dipped in reagent(15 seconds) then Swabbed with cotton
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ProcedureMicrostructure after polishing
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Procedure
Indentation• Used a 136° pyramidal diamond indenter
• Four indents of load 200gf were made as a boundary to specify area of indentation
• Indenter is pressed into each grain within specified area with a load of 15gf
• The indenter is pressed into the sample by an accurately controlled test force.
• The force is maintained for a specific dwell time, normally 10 – 15 seconds.
• The size of the indent is determined optically by measuring the two diagonals of the square indent.
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Procedure
Specified area for indentation:
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Procedure
Microstructure of the specimen after making all
the indents
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Calculation
where: P(=15kgf) is load d(avg) is average diagonalHV=Vickers Hardness no.
The size of the indent is determined optically by measuring the two diagonals of the square
indent.
Then Vickers hardness number is determined using d(avg):
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Observation
Hardness values varies from one grain to another
Maximum Hardness : 344
Minimum Hardness : 41.8
Standard Deviation: 57.133
y = 29057x-2.01
R² = 0.995
0
50
100
150
200
250
300
350
400
0 5 10 15 20 25 30
Hardness vs Average Diagonal
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Observation
0
2
4
6
8
10
12
14
16
18
20
1-50 51-100 101-150 151-200 201-250 251-300 301-350
Fre
qu
ency
of
Har
dn
ess
Hardness Intervel
Hardness Frequency Distribution
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Inference
Hardness values are not consistent throughout the structure.
We inferred from the frequency distribution that the hardness values are lying in a particular range for most of the grain.
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Acknowledgement
Dr. Nilesh Prakash Gurao
Ram Krishna Sir (Mechanical Lab, ACMS)
Chandrashekhar Sir, Samantha Ma’am
Mechanical Behavior Laboratory
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Thank You!