Enlargement of measurable strain range in biaxial cruciform test

In order to improve the accuracy of FEA in the assessment of crack and wrinkle risk, and in the amount of springback, the plastic anisotropy of a material should be measured over a wide strain range by a biaxial test, especially by a cruciform test. In this study, slit arm strengthening of a cruciform test specimen was investigated: its slit arms were melted by laser irradiation, and then mertensitized by quenching. One and a half times or larger measureable strain range was obtained by one laser irradiated line in a slit arm of a cruciform specimen compared with a specimen without laser irradiation.