Low temperature creep behaviour of pure aluminium and interstitial free steel at a constant stress

We carried out low temperature creep of pure aluminium and interstitial free steel under a constant stress condition. Constant creep rate, that is, steady state creep is observed for both materials in the relationship of the creep strain rate with the creep time. The apparent constant creep rate is not essential, because the curve of the creep rate against the creep strain yields no constant creep rate region. There are work hardening ( dissipative) process and damage process for the low temperature creep of ductile materials. In the former process, dislocations introduced during the deformation are rearranged in the stable form of the cell structure. The self oganization is resulted from the consumption of the external applied stress. In the latter process, the micro void formation takes place and the true applied stress is increased. The mechanical characteristic is distinguished by the parameter (partial derivative sigma/partial derivative epsilon) = H or D for a constant strain rate. The positive value is for a dissipative process and the negative one for a damage process.