Examples of aluminium fractography
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Examples of Aluminium Fractography. Professor M Neil James [email protected] Department of Mechanical & Marine Engineering University of Plymouth Drake Circus, Plymouth PL4 8AA ENGLAND. Bend fatigue of 6261-T6 alloy Torsion fatigue of 6061-T6 alloy Ductile fracture of 6061-T6 alloy

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Examples of Aluminium Fractography

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Examples of aluminium fractography

Examples of Aluminium Fractography

Professor M Neil James

[email protected]

Department of Mechanical & Marine Engineering

University of Plymouth

Drake Circus, Plymouth PL4 8AA

ENGLAND

Fractography Resource - [email protected]


Contents use the hyperlinks to navigate around this resource

  • Bend fatigue of 6261-T6 alloy

  • Torsion fatigue of 6061-T6 alloy

  • Ductile fracture of 6061-T6 alloy

  • Fatigue of 8090-T8511 Al-Li alloy

  • Ductile fracture of 8090-T8511 Al-Li alloy

  • Bend fatigue of friction stir welded 5383-H321 alloy

  • Ductile fracture of 5383-H321 alloy

  • Defects in an aluminium-silicon-magnesium casting alloy

Contents – Use the hyperlinks to navigate around this resource

Fractography Resource - [email protected]


Bend fatigue of 6261 t6 alloy

Al 0.74Mg 0.63Si 0.19Fe 0.26Cu 0.025Zn 0.020Ti

Peak aged - PS = 282 MPa – Parent Plate (I-beam flange)

Bend fatigue of 6261-T6 alloy

Linear growth rate regime ~ 10-4 mm/cycle

Arrows indicate grain boundaries

Original magnification 80x

Fractography Resource - [email protected]


Bend fatigue of 6261 t6 alloy1

Al 0.74Mg 0.63Si 0.19Fe 0.26Cu 0.025Zn 0.020Ti

Peak aged - PS = 282 MPa – Crack at weld toe of cover plate

Bend fatigue of 6261-T6 alloy

Linear growth rate regime ~ 10-4 mm/cycle

The HAZ appears to be embrittled, and cleavage facets are present

Original magnification 20x

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Fractography Resource - [email protected]


Torsion fatigue of 6061 t6 alloy

Al 0.8-1.0Mg 0.4-0.8Si 0.70Fe 0.15-0.40Cu 0.25Zn 0.15Ti 0.15Mn

Peak aged - PS = 312 MPa – extruded rod

Torsion fatigue of 6061-T6 alloy

Crack initiation region

Original magnification given by micron marker

Fractography Resource - [email protected]


Torsion fatigue of 6061 t6 alloy1

Al 0.8-1.0Mg 0.4-0.8Si 0.70Fe 0.15-0.40Cu 0.25Zn 0.15Ti 0.15Mn

Peak aged - PS = 312 MPa – extruded rod

Torsion fatigue of 6061-T6 alloy

Crack initiation region – smooth areas of slip band cracking are present

Original magnification given by micron marker

Fractography Resource - [email protected]


Torsion fatigue of 6061 t6 alloy2

Al 0.8-1.0Mg 0.4-0.8Si 0.70Fe 0.15-0.40Cu 0.25Zn 0.15Ti 0.15Mn

Peak aged - PS = 312 MPa – extruded rod

Torsion fatigue of 6061-T6 alloy

Crack growth appears to have a component of MVC

Original magnification given by micron marker

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Fractography Resource - [email protected]


Ductile fracture of 6061 t6 alloy

Al 0.8-1.0Mg 0.4-0.8Si 0.70Fe 0.15-0.40Cu 0.25Zn 0.15Ti 0.15Mn

Peak aged - PS = 312 MPa – extruded rod

Ductile fracture of 6061-T6 alloy

Precipitate particles are present at the bottom of voids

Original magnification given by micron marker

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Fractography Resource - [email protected]


Fatigue of 8090 t8511 al li alloy

Al 2.37Li 1.19Cu 0.82Mg 0.11Zr

Peak aged - PS = 300 MPa – large extrusion 120 mm by 100 mm

Fatigue of 8090-T8511 Al-Li alloy

Heat treatment leads to grain boundary precipitation of Al2CuMg, which affects crack growth

IG regions are often present

Original magnification given by micron marker

Fractography Resource - [email protected]


Fatigue of 8090 t8511 al li alloy1

Al 2.37Li 1.19Cu 0.82Mg 0.11Zr

Peak aged - PS = 300 MPa – large extrusion 120 mm by 100 mm

Fatigue of 8090-T8511 Al-Li alloy

Heat treatment leads to grain boundary precipitation of Al2CuMg, which affects crack growth

IG regions are often present

Original magnification given by micron marker

Fractography Resource - [email protected]


Fatigue of 8090 t8511 al li alloy2

Al 2.37Li 1.19Cu 0.82Mg 0.11Zr

Peak aged - PS = 300 MPa – large extrusion 120 mm by 100 mm

Fatigue of 8090-T8511 Al-Li alloy

Heat treatment leads to grain boundary precipitation of Al2CuMg, which affects crack growth

Typical IG region at high magnification

Original magnification given by micron marker

Fractography Resource - [email protected]


Fatigue of 8090 t8511 al li alloy3

Al 2.37Li 1.19Cu 0.82Mg 0.11Zr

Peak aged - PS = 300 MPa – large extrusion 120 mm by 100 mm

Fatigue of 8090-T8511 Al-Li alloy

Heat treatment leads to grain boundary precipitation of Al2CuMg, which affects crack growth

'Blocky' striated fatigue also occurs

Original magnification given by micron marker

Fractography Resource - [email protected]


Fatigue of 8090 t8511 al li alloy4

Al 2.37Li 1.19Cu 0.82Mg 0.11Zr

Peak aged - PS = 300 MPa – large extrusion 120 mm by 100 mm

Fatigue of 8090-T8511 Al-Li alloy

Heat treatment leads to grain boundary precipitation of Al2CuMg, which affects crack growth

Regions of 'normal' striated fatigue also occur

Original magnification given by micron marker

Fractography Resource - [email protected]


Fatigue of 8090 t8511 al li alloy5

Al 2.37Li 1.19Cu 0.82Mg 0.11Zr

Peak aged - PS = 300 MPa – large extrusion 120 mm by 100 mm

Fatigue of 8090-T8511 Al-Li alloy

Interface between ductile fast fracture (MVC) and fatigue is shown here

Original magnification given by micron marker

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Fractography Resource - [email protected]


Ductile fracture of 8090 t8511 al li alloy

Al 2.37Li 1.19Cu 0.82Mg 0.11Zr

Peak aged - PS = 300 MPa – large extrusion 120 mm by 100 mm

Ductile fracture of 8090-T8511 Al-Li alloy

Typical MVC is shown here

Original magnification given by micron marker

Back to Contents

Fractography Resource - [email protected]


Bend fatigue of 5383 h321 alloy

Al 4.43Mg 0.78Mn 0.12Si 0.21Zn 0.09Fe 0.09Cu 0.09Cr

Strain hardened – quarter hard - PS = 272 MPa – single pass friction stir welded

Bend Fatigue of 5383-H321 alloy

Crack initiation is from tool travel marks

Original magnification given by micron marker

Fractography Resource - [email protected]


Bend fatigue of 5383 h321 alloy1

Al 4.43Mg 0.78Mn 0.12Si 0.21Zn 0.09Fe 0.09Cu 0.09Cr

Strain hardened – quarter hard - PS = 272 MPa – single pass friction stir welded

Bend Fatigue of 5383-H321 alloy

High cycle fatigue shows signs of the underlying microstructure

Original magnification given by micron marker

Fractography Resource - [email protected]


Bend fatigue of 5383 h321 alloy2

Al 4.43Mg 0.78Mn 0.12Si 0.21Zn 0.09Fe 0.09Cu 0.09Cr

Strain hardened – quarter hard - PS = 272 MPa – single pass friction stir welded

Bend Fatigue of 5383-H321 alloy

Low cycle fatigue appears more generally ductile striated growth

Original magnification given by micron marker

Fractography Resource - [email protected]


Bend fatigue of 5383 h321 alloy3

Al 4.43Mg 0.78Mn 0.12Si 0.21Zn 0.09Fe 0.09Cu 0.09Cr

Strain hardened – quarter hard - PS = 272 MPa – single pass friction stir welded

Bend Fatigue of 5383-H321 alloy

Low cycle fatigue shows clear striations at high magnification

Original magnification given by micron marker

Fractography Resource - [email protected]


Bend fatigue of 5383 h321 alloy4

Al 4.43Mg 0.78Mn 0.12Si 0.21Zn 0.09Fe 0.09Cu 0.09Cr

Strain hardened – quarter hard - PS = 272 MPa – single pass friction stir welded

Bend Fatigue of 5383-H321 alloy

SP FSW can lead to partial-fusion defects in the weld nugget (also called 'kissing' bonds)

Original magnification given by micron marker

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Fractography Resource - [email protected]


Ductile fracture of 5383 h321 alloy

Al 4.43Mg 0.78Mn 0.12Si 0.21Zn 0.09Fe 0.09Cu 0.09Cr

Strain hardened – quarter hard - PS = 272 MPa – single pass friction stir welded

Ductile Fracture of 5383-H321 alloy

MVC in this alloy

Original magnification given by micron marker

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Fractography Resource - [email protected]


Defects in welded al si mg casting alloy

Defects in welded Al-Si-Mg casting alloy

Intergranular-interdendritic hot cracking

Magnification given by micron marker

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Fractography Resource - [email protected]


Defects in welded al si mg casting alloy1

Defects in welded Al-Si-Mg casting alloy

Wormhole porosity

Magnification given by micron marker

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Fractography Resource - [email protected]


Defects in welded al si mg casting alloy2

Defects in welded Al-Si-Mg casting alloy

Possible layer porosity

Magnification given by micron marker

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Fractography Resource - [email protected]


Defects in welded al si mg casting alloy3

Defects in welded Al-Si-Mg casting alloy

Illustration of the formation of layer porosity during solidification of an aluminium alloy where the freezing range is large and/or the temperature gradient is low (i.e. solidification occurs over an extended time).

Magnification given by micron marker

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Fractography Resource - [email protected]


Defects in welded al si mg casting alloy4

Defects in welded Al-Si-Mg casting alloy

HC+UC

Fatigue crack (F) which has been initiated by a region of hot cracking and undercut/slag inclusion (HC+UC).

Magnification given by micron marker

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F

Fractography Resource - [email protected]


Defects in welded al si mg casting alloy5

Defects in welded Al-Si-Mg casting alloy

Increasing the size of the image reveals faint striation-like markings whose spacing indicate a fast growth rate of ~ 1x10-3 mm/cycle of load at this point.

Magnification given by micron marker

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Fractography Resource - [email protected]


Defects in welded al si mg casting alloy6

Defects in welded Al-Si-Mg casting alloy

Illustrative crack growth rate curve for an Al alloy; a crack growth rate of 1x10-3 mm/cycle of load lies in Region III of the curve.

Magnification given by micron marker

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Fractography Resource - [email protected]


Defects in welded al si mg casting alloy7

Defects in welded Al-Si-Mg casting alloy

Parts of both the fatigue and the brittle fracture surfaces, as well as some regions of porosity show the presence of needles, which EDS indicated are likely to be the iron-rich β-phase, Al5FeSi.

This phase is known to detrimentally influence the mechanical properties of Al-Si-Mg alloys.

Magnification given by micron marker

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Fractography Resource - [email protected]


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