INVESTIGATION OF THE NATURE OF STRUCTURAL DAMAGE IN METAL-FORMING PROCESSES.
Final rept., Jan 66-Apr 67,
GENERAL ELECTRIC CO SCHENECTADY N Y RESEARCH AND DEVELOPMENT CENTER
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The present investigation is the third phase of a broad program undertaken with the goal of understanding the nature of structural damage during metal-forming processes and, in particular, the role of the hydrostatic component of the stress during deformation on the generation of such damage. Sheet drawing experiments were performed on 6061-T6 aluminum alloy, 60-40 unleaded brass, and Ferrovac E under a variety of experimental conditions. The ability to assess the resulting damage in terms of changes in the density of the metals after drawing has been improved over that of previous studies by modifications in the density measuring facility. Among the improvements has been the adoption of diethyl phthalate as the immersion fluid replacing water and the development of a complete analytical expression for the density using the three-weighing techniques which factors in minor changes in temperature and air buoyancy. The results of drawing experiments on the aluminum alloy indicate that conditions producing the same state of hydrostatic stress at the midplane of the strip generate nearly comparable damage. There is a minor effect of die angle. The density of that portion of the strips near the midplane, where the stress state is most highly tensile, is substantially lower than the average strip density.
- Fabrication Metallurgy