B-58 WING - PYLON BOX FORGING - MECHANICAL PROPERTIES - DETERMINATION OF
Abstract
A proposed design change for the fabrication of the inboard pylon attach bracket 4W3306-29 and -30, used on B-58 airplanes, involved forging a single SAE 4335 mod. steel billet into the rough shape of the wing-pylon box which would then be machined to the final configuration. In general the mechanical properties of the SAE 4335 mod. steel forging compared favorably with those obtained from the bar stock. Those areas tested in the forging had lowered ductility and fatigue strength were explained by reason of proximity to the forging parting plane, transverse grain direction, and/or inclusions. At the 190 ksi heat treat level, the static strength of the forging was not notch sensitive to stress concentrations as high as K sub t equals 11. The majority of the fatigue cracks in the smooth fatigue specimens started at inclusions which were exposed to the specimen outer surface. In those specimens where the inclusions were concentrated or unusually large, the fatigue strength of the material was drastically reduced. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 16, 1962
- Accession Number
- AD0272163
Entities
People
- R.l. Jones
Organizations
- General Dynamics