Accession Number : ADA140832

Title :   Processing and Properties of Airframe Materials.

Descriptive Note : Annual rept. 1 Jan-31 Dec 83,


Personal Author(s) : Wert,J A ; Ghosh,A K ; Chesnutt,J C ; Rhodes,C G

PDF Url : ADA140832

Report Date : Feb 1984

Pagination or Media Count : 51

Abstract : This annual report describes progress during the first year of the three year research program to study the relationship between microstructure and processing conditions, and the effect of processing conditions on the performance of structural airframe materials. Part I of this program is examining the influence of beta processing methods on the interaction of fatigue cracks with the microstructural elements. three beta phase processing methods have been chosen to provide variations in beta phase continuity and alpha phase plate size. The microstructure of the beta processed materials has been quantitatively characterized using SEM, TEM and STEM. Fatigue crack propagation results are also presented for each of the beta annealing treatments. In Part II, the micromechanics of superplastic deformation behavior. Experiments have been performed with 7475 Al having various grain sizes. The flow stress vs strain rate behavior for the mixed grain size materials is best described using the iso-strain rate concept. Observations of dynamic grain growth and dynamic recrystallization have led to new perceptions of how these processes may alter the mechanical response of the materials during superplastic deformation. Based on these observations, the new model of the superplastic deformation process is outlined. (Author)

Descriptors :   *Metals, *Airframes, *Structural properties, *Mechanical properties, Construction materials, Aluminum, Titanium, Fatigue(Mechanics), Plastic deformation, Crack propagation, Cracks, Structural response, Stresses, Recrystallization, Dynamics, Processing, Methodology, Microstructure, Grain size, Annealing, Research management

Subject Categories : Aircraft
      Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE