Ti-6Al-4V alloy has come to be widely used in industrial products. In recent years, hexagonal-close-packed (HCP) metals have attracted attention for use as practical materials. Heat-affected zones on laser cutting and irradiation surfaces exhibit changes in crystal grains. Moreover, their textures differ from those of other regions. Therefore, we used laser-processed Ti-6Al-4V alloy to investigate changes in crystal grain and texture characteristics. The crystal orientation was measured using an electron backscatter diffraction (EBSD) apparatus. Inverse pole figure (IPF) maps were measured from the laser cutting and irradiation surfaces. The results demonstrate that Ti-6Al-4V alloy has a martensitic structure that is attributable to laser irradiation.

A material testing apparatus for measuring the biaxial deformation behavior of a polymer tube is developed to quantitatively evaluate the deformation behavior of polymeric materials. The testing apparatus can apply axial force and internal pressure to a tubular specimen. A noncontact strain measurement system is also developed, and the biaxial strain components and the radius of curvature in the axial direction of the specimen are continuously measured to control the stress path applied to the specimen. Polyethylene tubes with an outer diameter of 17 mm and a thickness of 2 mm are used as test specimens, that are subjected to linear stress paths with stress ratios of σ_φ :σ_θ =1:0, 4:1, 2:1, 4:3, 1:1, 3:4, 1:2, 1:4, and 0:1, where σ_φ and σ_θ are the axial and circumferential stress components applied to the center of the bulging specimen, respectively. Biaxial stress-strain curves are successfully measured for every linear stress path at a nearly constant logarithmic strain rate of 1×10^-3 s^-1. A maximum equivalent strain of up to 0.71 is achieved for a specimen with a stress path of σ_φ :σ_θ =2:1. The contours of equal work plotted in the principal stress space show a significant anisotropy of the test material.