The large impact torsion testing machine which has recently been designed and constructed by the present authors, has the capacity of 100kg-m and the rotating speed from 100rpm to 2600rpm. This machine is fit to make intermittent loading, the detection of axial stress caused during the torsional deformation and the tests under combined stress by adding tensile deformation.The blue shortness and the reduction of twist ductility during the α-γ transformation of mild steel and 13% chromium stainless steel have been studied under various deformation rates. The brittle fracture of thin walled tubular specimens of mild steel with several grain sizes has been tested under various strain rates and low temperature, and the transition temperatures have been compared with that of impact tension and Charpy test. Finally the intermittent impact torsion has been carried out in order to evaluate the hot-working behavior of mild steel.