MSE 201 LAB Section 1

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MSE 201 LAB ( Section 1 Section 2) TA Anoop
Samant Email asamant_at_utk.edu Phone
974-5160 Mail Box DO 420 Course Website
http//www.engr.utk.edu/asamant/ http//www.onl
ine.utk.edu/ (MSE201 LAB- DR.MEEK )
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LAB I

• Mechanical Properties of Steels Tensile,
  Hardness, and Impact Testing

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Test 1 Tensile Testing
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Introduction

• PLAIN CARBON STEEL
• Designation 1018
• 10 PLAIN CARBON
• (0.02-2.14C, Trace Mn, Si, S, Balance Fe)
• 18 0.18 Carbon
• Good structural strength
• Cheap
• - Poor Corrosion Resistance

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Sample Conditions

• Cold Rolled
• Annealed
• 870C for 2 hours
• Slow cooled (Furnace Anneal)

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What is Measured?

• Load (Pounds Force)
• Stress Engineering Stress Conversion
• Displacement
• Crosshead Movement
• Strain from Extensometer
• Adjectives used Strong or Weak material.

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Tensile Testing

• Measures Load vs. Displacement (Elongation)
• Mechanical properties
• obtained from plot
• UTS
• 0.2 Yield Strength
• Youngs Modulus
• Modulus of Resilience
• Racquetball vs. silly Putty
• Elongation
• Ductility
• Stress at Fracture
• Engineering and True
• Toughness

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What About Dislocations?

• Necessary to move atoms around
• Ping pong balls in box
• Heat gets rid of them
• Atomic vibrations
• Re-created when strained
• Gives rise to upper and lower yield points
• Similar to static vs. sliding friction

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Dislocation Example Movie
Pure Metal
Alloy
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Load vs. Position (Cross Head Motion)
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Stress vs. Strain (from Extensometer)
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The Lomer-Cottrell Lock - Annealed Sample
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RUN TENSILE TESTS!

• Samples Cold rolled Annealed 1018

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Test 2 Hardness Testing

• Hardness - Resistance to plastic deformation
• Adjectives used - Hard or Soft
• Advantages
• Simple procedure
• Inexpensive to conduct
• Nondestructive (well, sort of)
• tensile strength can be estimated from hardness

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The Rockwell Scales

• Hardness numbers without unit
• Includes multiple scales
• Different loading levels different indenters
• HRC Hard Steels -gt 150kgf diamond indenter
• HRB Softer Steels -gt 100kgf 1/16 in. Steel
  ball indenter
• HRF Bronzes -gt 60kgf 1/16 in. Steel ball
  indenter
• Superficial scales available for thin samples
  when needed

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Conversion of Data to DPH

• Vickers hardness (HV) - DPH (Diamond Pyramid
  Hardness)
• DPH covers entire range from HRF up to HRC

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Roundness Correction
Curved cause hardness is read lower than the
actual value. (See ASTM E18 for correction tables)
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Precautions for Hardness Measurement

• Clean Sample Surface
• Bulk Sample - sample thickness gt 10 times depth
  of indent
• Indentations shall to be 3 - 5 times the diameter
  of the indent apart
• Corrections must be made for round surfaces.
  (ASTM E-18)

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Perform Hardness Tests

• Use HRB/HRF Scale
• Load 100/60 kgf
• Indenter 1/16 steel ball indenter

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Task 3 Charpy Testing
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Ductile-to-Brittle Transition (DBT)
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Charpy V-Notch Impact Tests

• Measures Energy Absorbed upon Impact lateral
  contraction of the samples
• Used Energy Absorbed-Temperature plot to find
  DBT temperature
• Adjectives used - Tough or Brittle.
• Dull fracture - shear or ductile.
• Shiny fracture - cleavage or brittle.

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Fracture Surfaces
Cleavage Brittle
Dimple Tough
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The Set-up

• Procedure - ASTM E23
• Material - Cold Rolled 1018
• Test Temperatures
• Boiling Water (100 ?C)
• Room Temp ( 25 ?C)
• Ice Water (0)
• Dry Ice (-78 C )
• Liquid Nitrogen (-196 ?C)

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Perform Charpy Tests