Internal stresses during creep of magnesium alloys at 523 K

Strain transient dip tests have been used for the measurement of internal and effective stresses in minimum creep rate stages of several magnesium-based alloys at 523 K. Values of the internal stresses well reflect the creep resistance levels of the investigated alloys. The applied stress exponent n of the minimum creep rate ε ˙ min equals or exceeds values of six in all the investigated alloys. On the other hand, a very low value of two for the effective stress exponent m of ε ˙ min was obtained independent of alloy structure. The experimental internal stress in creep is comparable with the internal stress determined by means of stress relaxation tests in the course of stress–strain tests under similar stresses at the testing temperature.