Evolution of dislocation structure in martensitic steels:: the subgrain size as a sensor for creep strain and residual creep life

The results on the evolution of the dislocation structure in martensitic CrMoV-steels published by two research groups are shown to be consistent: The steady state dislocation spacings vary in inverse proportion to shear modulus normalized stress, the subgrains grow with strain at a rate which is determined by the initial subgrain size w(0), the steady state subgrain size w(infinity), and the strain rate, independent of the composition of the material. At constant stress and temperature the strain epsilon and the subgrain size w are uniquely related by epsilon = epsilon(w)In[log(w(0) / w(infinity)) / log(w / w(infinity))] with epsilon(w) = 0.12. Thus wean be used as a sensor for strain and, if the relation between strain and time is known. for the residual creep life.