Hot crack formation in continuously cast steel is significantly influenced by the mechanical properties of the solid shell near its solidus temperature. Herein, a new method to study the high-temperature mechanical behavior of the solidifying steel shell is introduced. In this method, an apparatus is designed utilizing an electric cylinder that is controlled by a servomotor to apply a specified amount of strain to the solidifying steel shell at a controlled strain rate. A special mold configuration is developed to control the dendrite growth in the direction perpendicular to the applied strain and to ensure that the strain is applied in the region of controlled shell growth. Real-time load, displacement, and temperature data are monitored by a computer-assisted data acquisition system. The temperature profile of the casting is predicted by MAGMASOFT and compared with experimental data. The Fourier thermal analysis method is applied to calculate a solid fraction and coupled with the temperature profile to determine the solid shell thickness during the test. The maximum strength at different temperatures for a medium-carbon steel is determined and compared with that from the submerged split-chill tensile test and hot tensile tests.