Why does uniform elongation in ferritic stainless steel exhibit a decreasing behavior with an increase in temperature, even after the DSA regime?

This decreasing behavior in uniform elongation is presented in the paper from Choudhary B.K. et al, Influence of Temperature and Strain Rate on Tensile Deformation and Fracture Behavior of P92 Ferritic Steel (https://doi.org/10.1007/s11661-013-1869-6).

I am also observing the same behavior on an AISI 430 ferritic stainless steel and would like to request some assistance on this matter. 

Thank you very much,

Guilherme Soares