Stress rupture data are sometimes correlated with the Dorn parameter, θ = t exp[-Q/(RT )], where t is the rupture time, T is absolute temperature, and θ is assumed to depend only on stress. If this parameter correctly described a set of data, then a plot of log(t) versus 1/T for data at a single level of stress would be a straight line. If the Larson-Miller parameter correctly correlates the data, a plot of data at constant stress (therefore constant P) of log (t) versus 1/T also would be a straight line.
A. If both parameters predict straight lines on log (t) versus 1/T plots, are they really the same thing?
B. If not, how do they differ? How could you tell from a plot of log (t) versus (1/T ) which parameter better correlates a set of stress rupture data?