Failure Analysis of EN24 Steel Shear Bolt Used in Space Programme
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Abhay K. Jha
Abstract
Cadmium electrodeposited EN24 steel shear bolts were used in space programme. Recently, one of five bolts subjected to wedge test at 18 Nm torque encountered failure. Fracture surface of failed bolt had two distinct regions, when viewed under scanning electron microscope. Outer region consisted of brittle features while inner region had ductile failure. Detailed investigation revealed that the bolt failure was due to hydrogen embrittlement. Electro-deposition of cadmium was main source for hydrogen entrapment, which could not be compelled out by post plating baking treatment.
Kurzfassung
In einem Raumfahrtprogramm kamen elektrolytisch mit Cadmium beschichtete Scherbolzen aus EN24-Stahl zum Einsatz. Unlängst versagte einer der fünf Bolzen bei einem Keiltest bei einem Drehmoment von 18 Nm. Die Bruchfläche des entsprechenden Bolzens wies bei Betrachtung unter dem Rasterelektronenmikroskop zwei unterschiedliche Bereiche auf. Der äußere Bereich hatte Merkmale eines spröden Versagens, während der innere Bereich einen Verformungsbruch aufwies. Eine eingehende Untersuchung zeigte, dass der Bolzen aufgrund von Wasserstoffversprödung versagte. Die elektrolytische Abscheidung von Cadmium war Hauptgrundlage für die Ansammlung von Wasserstoff. Dieser konnte durch die nach dem Beschichten erfolgende Wärmebehandlung im Ofen nicht aus dem Werkstoff herausgetrieben werden.
References / Literatur
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© 2014, Carl Hanser Verlag, München
Articles in the same Issue
- Contents/Inhalt
- Contents
- Editorial
- Editorial
- Technical Contributions/Fachbeiträge
- Characterization of Frictional Stressed White Etching Layers out of Cutting Tools by Means of Transmission Electron Microscopy (TEM)
- Grain Size Measurement in Experimental Co-Re-based Alloys to Study Grain Coarsening, Part I
- Colour Metallography of Cast Aluminium Alloys
- Failure Analysis of EN24 Steel Shear Bolt Used in Space Programme
- Meeting Diary/Veranstaltungskalender
- Meeting Diary
Articles in the same Issue
- Contents/Inhalt
- Contents
- Editorial
- Editorial
- Technical Contributions/Fachbeiträge
- Characterization of Frictional Stressed White Etching Layers out of Cutting Tools by Means of Transmission Electron Microscopy (TEM)
- Grain Size Measurement in Experimental Co-Re-based Alloys to Study Grain Coarsening, Part I
- Colour Metallography of Cast Aluminium Alloys
- Failure Analysis of EN24 Steel Shear Bolt Used in Space Programme
- Meeting Diary/Veranstaltungskalender
- Meeting Diary
