Temperature dependence of the dynamic fracture toughness of the alloy Incoloy 800 after cold work

Instrumental impact tests were performed on prefatigued charpy-impact tests specimens of the material Incoloy 800 in the as-received state and after 5%, 10% and 25% cold work in the temperature range 293 ≤ T/K ≤ 1223. The impact energi es were determined with different methods, the agreement was excellent. The temperature dependence of the impact energies exhibit an intermediate maximum at 673 K (400deg C). This maximum is more or less suppressed with increasing cold work. The temperature dependence of the fracture toughness reveals a decrease with increasing temperature. The decrease is most pronounced in the as-received state. The isothermes of the impact energies as a function of cold work show that between the as-received state and 5% cold work a large decrease in the energy can be observed. This is very strongly pronounced at room temperature and at 673 K (400deg C). In this region the usual degree of cold work can be found manufacturing components. From this point of view of weakness of the material with respect to its mechanical properties can be expected. (orig.)