The Influence of Plastic Anisotropy on the Localized Necking of Ti-6Al-4V.

摘要

The influence of plastic anisotropy on the localized necking behavior of strongly textured Ti-6Al-4V sheet has been investigated. Tensile tests as well as punch-stretch tests have been performed on strongly textured sheet with either normal or planar anisotropy and with R-values ranging from 0.5 to 12. In uniaxial tension, a high R-value increases the post-uniform elongation but has no significant effect on the uniform elongation. The effects of the R-value on the forming limit diagram depends on the loading path. A high R-value enhances the limit strain at the onset of localized necking in the negative minor strain region, but has little or no effect at plane strain. The dependence of the limit strain on the R-value in the negative minor strain region of the forming limit diagram can be understood in terms of a critical thickness strain criterion. Fracture appears to intervene prior to localized necking in the positive minor strain region of the FLD. (Author)