A new tensile creep model that integrates the tensile strength at creep temperature is

investigated for its generic applicability in predicting the long-term creep strengths from

short-term creep test data for high Cr creep-resistant steels using creep and tensile strength

data measured for a grade of 11Cr steel. The results show that, when the long-term creep

strengths are specified by stresses producing the required minimum creep rate, they can be

accurately predicted using short-term creep test data. However, when they are specified by

stresses giving the required creep rupture time, using only short-term creep test data will lead

to over-predictions. The microstructure evolution origin of such over-predictions is traced to

the Z-phase precipitation during creep in creep-resistant steels with more than 9 wt.% Cr. The

conventional concept on the relationship between creep test stress and creep mechanisms is

also re-evaluated in light of the new results.