DETERMINATION OF HARDNESS OF TITANIUM SAMPLE Priyanshu 12518 Raghvendra 12528 Proneet 12520 Rahul 12535 Punkesh 12522 Ashutosh 12542 Tuesday Group 2 2014 Dept. of Materials Science & Engineering
DETERMINATION OFHARDNESS OF TITANIUM SAMPLE
Priyanshu 12518 Raghvendra 12528Proneet 12520 Rahul 12535Punkesh 12522 Ashutosh 12542
Tuesday Group 22014
Dept. of Materials Science & Engineering
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
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
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.
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
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
ProcedureMicrostructure after polishing
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.
Procedure
Specified area for indentation:
Procedure
Microstructure of the specimen after making all
the indents
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):
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
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
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.
Acknowledgement
Dr. Nilesh Prakash Gurao
Ram Krishna Sir (Mechanical Lab, ACMS)
Chandrashekhar Sir, Samantha Ma’am
Mechanical Behavior Laboratory
Thank You!