Weld Repair of Cracked Defa Cannon Mount Frames,

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Abstract:

The weld repair of fatigue cracks found in the mounting frames of the Defa gun pack, fitted to Mirage III aircraft, is described. These cracks, caused by normal gun firing stresses, occurred well short of the frame design life as a result of metallurgical degradation in the form of a decarburized layer on the surface of the cast steel frames. Weld repair was by the Tungsten Inert-Gas process, using a low alloy Ni-Cr-Mo steel consumable. This produced a weld deposit with overmatching strength and toughness, with the aim of conferring a fatigue resistance at least equal to that of the sound parent metal, so as to prevent the recurrence of cracking. This performance was validated by laboratory fatigue-life S-N tests and fatigue crack growth measurements in weld metal and in sound casting. A detailed description is given of preweld preparation, the weld repair procedure, and postweld finishing including weld profile blending and surface protection. Author

Author(s):
Ritter, J. C. ; Phillips, R. H. ; Dixon, B. F.
Author Organization(s):
MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA)
Supplementary Note:
Includes errata sheet dated Aug 85.
Pagination:
0032

Security Markings

DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release

RECORD

Collection: TR
Identifying Numbers
Report Number(s):
MRL-R-956
 Subject Terms
Joint Capability Areas:
JCA_4.3_Maintain; JCA_5_Command and Control; JCA_5.3_Planning; JCA_6.4.1_Secure Information Exchange; JCA_3.2_Engagement; JCA_3_Force Application; JCA_3.2.1_Kinetic Means; JCA_6_Net Centric; JCA_6.4_Information Assurance; JCA_1_Force Support
Communities of Interest:
Weapons Technologies
Descriptor(s):
*WELDS, *REPAIR, *FRAMES, *GUN MOUNTS, METALS, MEASUREMENT, LAYERS, CRACKS, TOUGHNESS, STEEL, WELD METAL, SURFACES, DEPOSITS, CRACK PROPAGATION, SOUND, PROTECTION, CASTING, MOUNTS, FATIGUE(MECHANICS), GUNS, TUNGSTEN, FATIGUE TESTS(MECHANICS), WELDING, INTERIOR BALLISTICS
Field(s)/Group(s):
Metallurgy and Metallography, Ballistics
Report Date:
1985 Feb 01