[en] The effects of temperature (-75⁰C to 760⁰C) and cyclic strain rate (2 x 10^-4sec^-1 to 4 x 10^-1sec^-1) on the fracture mechanism were investigated using OFHC copper and Type 304 stainless steel under strain control. It was found that time dependent fracture predominates at high temperatures and low strain rates. However, at high strain rates the life was insensitive to temperature. The role of grain boundary migration on the fracture process was investigated. Grain boundary migration was found to be dependent on the strain rate for copper whereas for Type 304 stainless steel, grain boundary migration was inhibited at high temperature (760⁰C) due to the presence of precipitates at the grain boundaries. During strain cycling of OFHC copper and Type 304 stainless steel, creep damage cannot be summed to the fatigue damage to give a total damage of unity for failure, if only a single deformation and fracture mechanism is operating. The sense of the damage accumulation does not affect these findings. In general, the amount of previous damage has no influence on the damage accumulation which follows, if it is not of the same kind. (author)