M&AE 3272; Lecture #1B 27 January 2014 1 WSachse; 1/2014; M&AE 3272 1 The Fundamental Materials Triangle Structure Internal Structure and Composition of materials dictates their Properties Material Properties determine the Processing Operations that can be used Processing Operations change a material’s internal structure (“the material’s state evolves”) Properties Second Week – Mechanical Property Measurements M&AE 3272: Mechanical Property and Performance Laboratory Processing WSachse; 1/2014; Relationships – Two key questions : M&AE 3272 2 • What’s the relationship between material microstructure and mechanical properties? • What’s the relationship between material processing (solidification, forming and heat-treating) and the obtained material microstructures - and hence mechanical (and electrical and other) properties? • For a quick review check-out: • https://blackboard.cornell.edu/bbcswebdav/pid-1819946-dt-content-rid- 3419254_1/courses/10922_2013SP/Suppl%20Materials%20Lect2%20Material%20Prop erties.pdf
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M&AE 3272; Lecture #1B 27 January 2014
1
WSachse; 1/2014;M&AE 3272 1
The Fundamental Materials Triangle
Structure
Internal Structure and Composition of materials dictates their Properties
Material Properties determine the
Processing Operations that can be used
Processing Operations change a material’s
internal structure (“the material’s state evolves”)
Properties
Second Week – Mechanical Property Measurements
M&AE 3272: Mechanical Property
and Performance Laboratory
Processing
WSachse; 1/2014;
Relationships – Two key questions :
M&AE 3272 2
• What’s the relationship between material microstructure and mechanical properties?
• What’s the relationship between material processing (solidification, forming and heat-treating) and the obtained material microstructures - and hence mechanical (and electrical and other) properties?
Mechanical Properties are Critical -Consequences can be catastrophic!
M&AE 3272 4
Failure of:
• Bridges, Buildings, Structures
• Aircraft
• Medical Devices
Failure of F-15: The Air Force determined that the cause of the accident was a defective metal support beam . . .A failure of the upper right longeron, a critical support structure in the F-15C Eagle, caused the crash of a Missouri Air National Guard F-15C . . .The longeron didn't meet blueprint specifications. This defect led to a series of fatigue cracks in the right upper longeron which expanded under life cycle stress, causing the longeron to fail, thus initiating a catastrophic failure of the entire aircraft.
M&AE 3272; Lecture #1B 27 January 2014
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WSachse; 1/2014;
Properties of Metals:
M&AE 3272 5
Atomic Scale: Bonding
• Metallic
Microstructure
• Defects and Imperfections
• Crystal grains; Lamella
Useful Characteristics
• Mechanical Properties
• Electrical Conductivity
• Huge Information and Experience Base
• Machinability; Formability
Concerns:
• Fracture
• Fatigue
• Corrosion
• Oxidation
WSachse; 1/2014;
Measurement Challenge:
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You’re given a new super-material, just announced by HRL Laboratories which is claimed to be the lightestmaterial in the world! Ultralight Metallic Micro-lattices.
• Density: <10 mg/cm3
• Periodic array of connected, hollow
Nickel microtubes
• Octahedral unit cell
• Large strain (50%) deformations
• Completely reversible
How would you propose to determine the Young’s Modulusfor the Micro-lattice?
18-Nov-2011
M&AE 3272; Lecture #1B 27 January 2014
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WSachse; 1/2014;
1. Make a beam specimen, bend it and measure
the deflection.
2. Shake it and measure the modal frequencies.
3. Pull on a chunk of it and measure its stretch.
4. Push on a chunk of it and measure its
contraction.
5. Send a sound wave through it and measure the
travel time.
Measurement Challenge:
M&AE 3272 7
To determine the Young’s Modulus for a specimen of the new Ultralight Metallic Micro-lattice material, your best suggestion would be:
1. Make a beam specimen, bend it and measure
the deflection.
2. Shake it and measure the modal frequencies.
3. Pull on a chunk of it and measure its stretch.
4. Push on a chunk of it and measure its
contraction.
5. Send a sound wave through it and measure the
travel time.
WSachse; 1/2014;
Measurement Results: Young’s Modulus
M&AE 3272 8
Test the Microlattice specimen in compression and record the applied load P and measure the resulting
compression δδδδ of the sample. Stress: σσσσ = P/A
• O - Heated to recrystallization temperature; cooled to soaking temperature
(413-deg C; 3 hrs) then slowly cool (28-deg/hr) to 260-deg C
• T6 – Solution heat-treated, quenched and furnace aged
(Heated to 529-deg C; quenched; aged at 160-deg C for 18 hrs)
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ASTM Standard E8-04
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1. Scope
3. Terminology
5. Apparatus
6. Specimens
WSachse; 1/2014;
ASTM Standard E8-04
M&AE 3272 12
• Section 5, 5.2 – we will be using wedge grips
• Section 6, 6.2 – we will be using sheet type ½” wide standard specimens
• Section 7, 7.6 – we will be using a rate of separation of the two heads testing speed method. We will be using a rate determined by previous experience.
• Section 7, 7.7 – you will use the appropriate method to determine yield strength, when choice of a method is not clear, use the offset method.
• Mark on your Specimen where you will attach your Extensometer
• Mount your Specimen with Extensometer in the Testing Machine Grips
• Machine Control is via Instron Console and LabVIEW software
Set Maximum Extension: 1-inch; Maximum Rate: 0.01 in/sec
• Machine Data Collection is via LabVIEW software
Load (lbs) and Extensometer Reading (in)
• Remove specimen from grips; Return ram to initial position
• Download mechanical test data to thumb drive; Upload to LabArchives
• Convert data: σσσσ = P/A (P – Load; A – Cross-section Area of Specimen)
e = ∆∆∆∆L/L0
(∆∆∆∆L – Extensometer Reading; L0
– Initial Gage Length)
• Determine Young’s Modulus, Yield Stress; Ultimate Tensile Strength; Elongation at Fracture; Reduction of Area; Watch Units!
WSachse; 1/2014;
Ductility Measures:Elongation (%EL); Reduction of Area (%RA):
x100A
AARA%
o
fo −=
M&AE 3272 14
• Plastic tensile strain at failure:
Engineering tensile strain, ε
Engineering
tensile
stress, σ
smaller %EL
(brittle if %EL<5%)
larger %EL
(ductile if
%EL>5%)
• Another ductility measure:
• Note: %RA and %EL are often comparable.
--Reason: crystal slip does not change material volume.
--%RA > %EL possible if internal voids form in neck.
Lo LfAo
Af
100xL
LLEL%
o
of −=
Adapted from Fig. 6.13,
Callister 6e.
M&AE 3272; Lecture #1B 27 January 2014
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WSachse; 1/2014;
Comment on Reduction of Area (%RA):
]6/)4[( 321 www ++×]6/)4[( 321 ttt ++=Area
M&AE 3272 15
• Reduction of Area:
x100A
AARA
o
fo −=%
Lo LfAo
Af
= Thickness
= Widthw
t
WSachse; 1/2014;
Hardness Measurements:
Hardness Testing Methods: Provide a quick and easy determination of a number relatedto the flow stress of a material.
• Rockwell Hardness Test
• Rockwell Superficial Hardness Test
• Brinnel Hardness Test
• Vickers Hardness Test
• Microhardness Test
• Mohs’ Hardness Test
• Scleroscope; other hardness testing methods
M&AE 3272 16
M&AE 3272; Lecture #1B 27 January 2014
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Hardness: Common Measurement Procedures
WSachse; 1/2014;
Vickers Hardness Measurements:
Vickers Hardness Test:
• Indentation with a diamond indenter (right pyramid, angle 136-degs between faces)
• Load: 1 to 100 kgf for 10-15 seconds; then unload
• Measurement: Two diagonals of indentation measured and averaged
• Determination: Divide Load by area of sloping surfaces of indentation
M&AE 3272 18
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Hardness: Common Measurement Procedures
WSachse; 1/2014;
Rockwell Hardness Measurements:
M&AE 3272 20
Scale Indenter
Minor
Load
kgf
Major
Load
kgf
Total
Load
kgf
Value
of E
C Diamond Cone
10 140 150 100
B 1/16” Steel Ball
10 90 100 130
E 1/8”
Steel Ball
10 90 100 130
Rockwell Hardness Scales used in Lab:
Principle: The hardness test method consists of indenting a test material with a diamond cone or hardened steel ball indenter and after unloading measuring the permanent depth of penetration.
Procedure: The indenter is forced into the test material under a preliminary minor load F0 (Fig. 1A) usually 10 kgf. Then the major load is applied resulting in an increased penetration. The permanent increase in penetration is then used to compute the Rockwell Hardness number, HR:
HR = E - e [e: Units of 0.002mm]
M&AE 3272; Lecture #1B 27 January 2014
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Rockwell Hardness Measurements – TIPS!
Measurement Procedure:• After inserting the indenter, set the
minor load to R.• Set the load selector to the total test
load (e.g. 100 or 150 kgf.)• Press D/B to select test scale• Press AUTO• Place sample on anvil• Press Reset to read 0.0• Turn elevating handle until SET
lights up – If you overshoot the SET position, you will have to unload and repeat the test!
• Press START• Record Hardness value prior to
releasing load.• Release load• Repeat 10 times on each material
NOTE: Stay away from edges, and indents not too close to each other!
M&AE 3272 21
Rockwell Hardness Conversion Chart for Soft Materials
Linear Range: Rockwell B
Determine the Appropriate Hardness Scale to use.Procedure: Use the diamond indenter first; then 1/16”; then 1/8”.(If the test material is too hard, the ball-indenters might get damaged!)
ASTM E18-03:
• Section 5, 5.3 – we will be using a diamond indenter and 1/16 and 1/8-inch dia steel ball indenters
• Section 6, 6.3 and 6.4 – we will be using 1-inch diameter specimens
• Determine the density of your specimen(s). Repeat several times.
• Weigh your sample to determine its mass and then measure its diameter and thickness (H) .
• Then compute the volume of your specimen and the error in your volume determination: ∆∆∆∆V/V = 2∆∆∆∆r/r + ∆∆∆∆h/h .
• Couple the P-wave (with couplant; or S-wave transducer with pine tar –removed with alcohol!) to the ultrasonic source/receiver unit. Look for echoes on the oscilloscope display. Vary the pressure on the transducer and observe the cleanest possible echo pattern.
• Measure the wave arrival time for 2H, 4H, 6H, etc. How much do they vary? If you know how, use the delayed sweep of the oscilloscope.
• Can you estimate the error in your arrival time determination?
• Compute the longitudinal wavespeed.
• Repeat for using shear waves.
• Compute the Moduli of your material.
• Can you estimate the error in your modulus determination?
M&AE 3272 25
Procedure:
WSachse; 1/2014;
NEW: Ultrasonic Moduli Determination on LabArchives:
• Logon to LabArchives and in your Module 1 Folder add a `New Item’ where you will do the data input and data analysis.
• Create a spreadsheet for inputting echo arrival times, compute the echo time intervals. Input propagation length and estimated error.
• Compute the wavespeed(s) and the estimated error:
•� � � ∗�
�∆� � �
�∗∆�
�
�
∆�
�
�
• Enter the mass and estimated error; enter diameter and error.
• Compute the Volume and Density and Shear Modulus: Watch Units!
•� � ���∆� � ��∗∆�
�
�
∆�
�
�
M&AE 3272 26
Suggested Procedure: LabArchives Window
M&AE 3272; Lecture #1B 27 January 2014
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WSachse; 1/2014;
Your Material TestData Sheets:
0f /AA1RA% −=
00ff /L)L(L −=ε
ff00 LALA =
1RA% +=f
fεε
M&AE 3272 27
Expected Reduction
of Area:
Incompressibility:
(Available on Blackboard or
in your LabArchives Folder)
Now available as a
LabArchives Widget !
WSachse; 1/2014;
Your Report Summary:
M&AE 3272 28
Abstract: Mechanical Property Measurements
1. What was (were) the measurement problem(s) you
solved?
2. What procedures did you follow to solve the
problem?
3. What were your principal results?
4. What is the significance or impact of your results?
. . . Written in complete sentence form; 200-500
words (1 page) maximum. No figures.
Create in
MS-WORD;
Place into
your
Electronic
Lab
Notebook
M&AE 3272; Lecture #1B 27 January 2014
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WSachse; 1/2014;
Tasks to do this Week:
M&AE 3272 29
• Learn all about your specimen materials:Al: 6061-O; 6061-T6; C1050: Annealed; Oil Quenched
• Famililarize yourself with LabArchives. This will save you lots of time later when you process your data.
• Determine Expected Values of Density; Rockwell C; Yield Strength; Ultimate Tensile Strength; Elongation to Fracture; Reduction of Area; Modulus of Elasticity; Bulk Modulus and Poisson’s Ratio. Upload to LabArchives.
• Read the Handout for Module 1 Measurements.
• Peruse the ASTM Standards and read the relevant paragraphs.
• Lab Sections #401, #402, #403, #404, #409, #411 and #413 meet this week. Go to B30 Upson. Please be on-time!