Metallurgical Failure Investigation of Cracked Hook Nuts Used for Upending Gas Turbine Rotors on Site
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A. Neidel
Abstract
Two types of non-metallic inclusion stringers were found in so-called upending hook nuts, in the vicinity of an indication on the bore wall's surface, first, manganese sulfides that can be expected in this material, and second, endogeneous oxidic inclusions from the steelmaking process. The latter ones, too, can be expected to an extend in the structural steel that was used to make the hook nuts from. However, they are present in an excessive amount and were causative for the decohesions that produced the reported MT indications. The forging process which was employed to produce the semifinished product used to machine the hook nuts from was unable to fragment and disperse the non-metallic inclusions sufficiently as is usually the case.
Kurzfassung
Zwei Typen nichtmetallischer Einschlusszeilen wurden in den Muttern der Aufrichthaken in der Nähe einer Auffälligkeit auf der Oberfläche der Bohrungswand entdeckt: einerseits Mangansulfide, die in diesem Werkstoff zu erwarten sind, und andererseits vom Stahlherstellungsprozess herrührende endogene oxidische Einschlüsse. Letztere können bis zu einem gewissen Umfang ebenfalls in dem zur Herstellung der Hakenmuttern verwendeten Baustahl erwartet werden. Allerdings sind sie in erheblichen Ausmaß vorhanden und verursachten die Werkstofftrennungen, die zu den erwähnten MT-Prüfanzeigen führten. Der Schmiedevorgang, der zur Herstellung des Halbzeugs diente, aus dem die Hakenmuttern gearbeitet werden, führte nicht, wie es normalerweise der Fall ist, zur ausreichenden Fragmentierung und Dispersion der nichtmetallischen Einschlüsse.
References / Literatur
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© 2013, Carl Hanser Verlag, München
Articles in the same Issue
- Contents/Inhalt
- Contents
- Editorial
- Editorial
- Technical Contributions/Fachbeiträge
- Study of the Impact of Multiple Weld Repairs and Associated Stress-Relief Annealing on Mechanical Properties at Elevated Temperatures of Large Components Made of the Low-Alloy Steel 16Mo3
- Metallographic Preparation of Aluminium-Titanium Composites
- Growth Kinetics of CrC Coating Layers on AISI D3 Obtained by Thermo-Reactive Diffusion Technique
- Metallurgical Failure Investigation of Cracked Hook Nuts Used for Upending Gas Turbine Rotors on Site
- Meeting Diary/Veranstaltungskalender
- Meeting Diary
Articles in the same Issue
- Contents/Inhalt
- Contents
- Editorial
- Editorial
- Technical Contributions/Fachbeiträge
- Study of the Impact of Multiple Weld Repairs and Associated Stress-Relief Annealing on Mechanical Properties at Elevated Temperatures of Large Components Made of the Low-Alloy Steel 16Mo3
- Metallographic Preparation of Aluminium-Titanium Composites
- Growth Kinetics of CrC Coating Layers on AISI D3 Obtained by Thermo-Reactive Diffusion Technique
- Metallurgical Failure Investigation of Cracked Hook Nuts Used for Upending Gas Turbine Rotors on Site
- Meeting Diary/Veranstaltungskalender
- Meeting Diary
