examination and failure analysis of annealed paperclip by william burgess and khalid mansour

Examination and Failure Examination and Failure Analysis of Annealed Analysis of Annealed

PaperclipPaperclip

By William Burgess and Khalid By William Burgess and Khalid MansourMansour

Annealing ProcessesAnnealing Processes Annealing: Heat treatment wherein the Annealing: Heat treatment wherein the

microstructure and the material properties are microstructure and the material properties are altered.altered.

Samples separated using a vice-apparatus, Samples separated using a vice-apparatus, applying a uniaxial load.applying a uniaxial load.

All samples where heated above the austenization All samples where heated above the austenization temperature, then cooled differently.temperature, then cooled differently.

Samples where 1)Air cooled, 2) Furnace Cooled, Samples where 1)Air cooled, 2) Furnace Cooled, 3) Quenched and 4) Tempered (~3713) Quenched and 4) Tempered (~371ooC).C).

Microstructure PreparationMicrostructure Preparation

Heat and compress sample [Buehler Heat and compress sample [Buehler Mounting Press].Mounting Press].

4-Stage coarse Polish [Buehler].4-Stage coarse Polish [Buehler]. 2-Coarse fine artificial diamond polish with 2-Coarse fine artificial diamond polish with

alumina (Alalumina (Al22OO33).). 3% Nitric Acid (97% ethanol) etching.3% Nitric Acid (97% ethanol) etching. Alcohol swiping, cleaning.Alcohol swiping, cleaning. Investigate under optical microscope Investigate under optical microscope

[Nikon optiphot 300].[Nikon optiphot 300].

SEM PreparationSEM Preparation

Positioning samples on SEM apparatus.Positioning samples on SEM apparatus.

Gold and Argon Sputtering (~5 nm) for Gold and Argon Sputtering (~5 nm) for conductivity [Cressington Gold Sputter conductivity [Cressington Gold Sputter Coater].Coater].

Place sample on SEM, 20 kV accelerating Place sample on SEM, 20 kV accelerating voltage [Jeol Model JSM 35C].voltage [Jeol Model JSM 35C].

Higher-Magnification Higher-Magnification ComparisonsComparisons

200x Magnification 200x Magnification ComparisonComparison

Microstructure AnalysisMicrostructure Analysis

The softer the material, the The softer the material, the larger the grain size.larger the grain size.

In order of softest to In order of softest to hardest: Furnace Cooled, hardest: Furnace Cooled, Tempered, Air Cooled, Tempered, Air Cooled, Quenched.Quenched.

Mostly composed of Mostly composed of Pearlite with quenched Pearlite with quenched being fine pearlite, and being fine pearlite, and more of the coarse pearlite more of the coarse pearlite as hardness decreases.as hardness decreases.

SEM AnalysisSEM Analysis In general, the brittle fractures will have cleavage In general, the brittle fractures will have cleavage

features (sharp edges, jagged, fig 8.41,p.231) features (sharp edges, jagged, fig 8.41,p.231) and the ductile will have dimples (Round crater-and the ductile will have dimples (Round crater-like appearance, fig. 8.4a, pg. 196) on the SEM like appearance, fig. 8.4a, pg. 196) on the SEM level.level.

Difference in hardness if shown in the fracture Difference in hardness if shown in the fracture surfaces: The quenched sample will have most surfaces: The quenched sample will have most cleavage, and the furnace cooled will have the cleavage, and the furnace cooled will have the most dimples. Samples will have a combination most dimples. Samples will have a combination of both brittle and ductile characteristics.of both brittle and ductile characteristics.

The surface of a brittle fracture will be rather flat The surface of a brittle fracture will be rather flat and perpendicular to the axis of the applied load; and perpendicular to the axis of the applied load; the ductile will neck.the ductile will neck.

SEM Quenched SampleSEM Quenched Sample

SEM Air Cooled SamplesSEM Air Cooled Samples

SEM Tempered SampleSEM Tempered Sample

SEM Furnace Cooled SEM Furnace Cooled SamplesSamples

Shout outsShout outs Said Mansour, for use of Said Mansour, for use of

OCLI laboratory, OCLI laboratory, information, and information, and consultation.consultation.

Eric Edler(technician), for Eric Edler(technician), for assistance with the SEM assistance with the SEM images.images.

Cliff Alopa (physicist), for Cliff Alopa (physicist), for optical microscope optical microscope assistance.assistance.

Younes, for assistance in Younes, for assistance in annealing and preparing annealing and preparing specimen; for materials-specimen; for materials-science wisdom.science wisdom.