Takashi Sakai

Tensile specimens with equivalent plastic strains of 5 %, 10 %, 15 %, and 20 % were prepared for four specimen types: SS400, A1070-O, SUS304, and AZ31. The relationship between equivalent plastic strain and KAM (kernel average misorientation) was visualized and formulated from the results of EBSD (electron backscattered diffraction pattern) and OIM (orientation imaging microscopy) analyses. The results obtained in this study enabled quantitative understanding of the local strain introduced at each location during fabrication and deformation.

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.