デジタル画像相関法を用いた強度試験片の局所変形挙動評価に関する検討

Evaluation of local deformation behavior accompanying specimens by using digital image correlation

中田 隼矢; 谷川 博康

Nakata, Toshiya; Tanigawa, Hiroyasu

In tensile and fatigue testing, the deformation behavior of local domains of tungsten inert gas (TIG) and electron beam (EB) welded joint specimens of F82H was evaluated by using digital image correlation. For the tensile test specimens, tensile strength declined in the TIG welded joint material and ductility declined in both the EB and TIG welded joint materials. Because axial strain increased in the tempered heat affected zone (THAZ) and led to fracture of the TIG welded joint material, strength was considered to deteriorate. In fatigue testing, the number of cycles to fracture for the welded joint material decreased to less than 40-60% that for the base metal. For both fracture specimens, shear strain exhibited the largest value approximately between the fine grain HAZ (FGHAZ) and the THAZ, leading to fracture. Cavities and macrocracks formed in the FGHAZ and THAZ in the fracture specimens cross section, and geometrical damage possibly resulted in deterioration of fatigue lifetime.