One biaxial experiment is performed on an ultra-thin specimen made of 17-7 precipitation hardened stainless steel. An anti-wrinkling setup allows for the characterization of the mechanical behavior with Integrated Digital Image Correlation (IDIC). A sensitivity analysis assesses the amount of data available but reveals a discrepancy between observation and model that is interpreted as the occurrence of wrinkling in a confined boundary layer. From this observation, the identification is performed on a refined region of interest where reliable data are accessible. The calibration of parameters of various constitutive equations is performed. In particular, the identifiability of the so-called Hill-1948 model is analyzed.