Failure Analysis: Christmas Lights. Case Description & Hypotheses Fracture of the bent brass contact...
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Transcript of Failure Analysis: Christmas Lights. Case Description & Hypotheses Fracture of the bent brass contact...
![Page 1: Failure Analysis: Christmas Lights. Case Description & Hypotheses Fracture of the bent brass contact piece in various light bulb sockets The unbent contact.](https://reader031.fdocuments.in/reader031/viewer/2022020111/56649e735503460f94b73067/html5/thumbnails/1.jpg)
Failure Analysis:Christmas Lights
![Page 2: Failure Analysis: Christmas Lights. Case Description & Hypotheses Fracture of the bent brass contact piece in various light bulb sockets The unbent contact.](https://reader031.fdocuments.in/reader031/viewer/2022020111/56649e735503460f94b73067/html5/thumbnails/2.jpg)
Case Description & Hypotheses
• Fracture of the bent brass contact piece in various light bulb sockets
• The unbent contact never failed
• Brass composition from EDS:– Copper – 70%– Zinc – 30%
• Possible causes:– Overload– Fatigue– Corrosion
![Page 3: Failure Analysis: Christmas Lights. Case Description & Hypotheses Fracture of the bent brass contact piece in various light bulb sockets The unbent contact.](https://reader031.fdocuments.in/reader031/viewer/2022020111/56649e735503460f94b73067/html5/thumbnails/3.jpg)
Visual Examination
Contact removed by force
Contact easily removedOriginal failed contact
Corroded Contact
![Page 4: Failure Analysis: Christmas Lights. Case Description & Hypotheses Fracture of the bent brass contact piece in various light bulb sockets The unbent contact.](https://reader031.fdocuments.in/reader031/viewer/2022020111/56649e735503460f94b73067/html5/thumbnails/4.jpg)
Metallography(Longitudinal Sections)
Section of original broken part at fracture surface
Close-up of crack
Slip lines on unfractured
sample at bend
Slip lines on original
fractured sample
![Page 5: Failure Analysis: Christmas Lights. Case Description & Hypotheses Fracture of the bent brass contact piece in various light bulb sockets The unbent contact.](https://reader031.fdocuments.in/reader031/viewer/2022020111/56649e735503460f94b73067/html5/thumbnails/5.jpg)
Fractography
Fracture surface of original failed contact
(600x)
Fracture surface of brass exemplar broken with overload (600x)
![Page 6: Failure Analysis: Christmas Lights. Case Description & Hypotheses Fracture of the bent brass contact piece in various light bulb sockets The unbent contact.](https://reader031.fdocuments.in/reader031/viewer/2022020111/56649e735503460f94b73067/html5/thumbnails/6.jpg)
Conclusion• Stress Corrosion
Cracking (SCC)– Stress: bend– Corrosive
environment: Sulfur and Chlorine
• Solutions:- Coating/Electroplating- Socket design change- Annealing