The diffusivity of Mn in T316 austenitic stainless steel (16.8Cr-11.6Ni-2.5Mo-1.6Mn-0.04C-0.5wt%Si) was measured by using standard tracer techniques, and was also determined from concentration profiles obtained by microprobe analysis following vacuum annealing. There was good agreement between the diffusion coefficients obtained using both methods. The presence of a depleted layer was confirmed, and it was shown that the effusion of Mn during vacuum annealing was diffusion-rate controlled. The bulk diffusion of Mn at 1023 to 1473K was given by:

D (m2/s) = 4.12 x 10-5 exp[-260/RT]

The grain-boundary diffusion at 923 to 1273K was described by:

D (m3/s) = 1.6 x 10-12 exp[-187/RT]

A.F.Smith, R.Hales: Metal Science, 1975, 9[4], 181-4