Internal friction study of AISI 410 stainless steel

Abstract

From this study of the internal friction at low stresses of AISI 410 stainless steel in four different conditions of heat treatment the following conclusions are made: 1. 1. Young's modulus of the material is influenced by heat treatment and varies in the range 211 to 218 GPa. 2. 2. The internal friction is amplitude dependent and varies in the range 2 to 8 × 10 −4 for the different heat treatments and range of strain amplitudes investigated. 3. 3. The break away strain amplitude of the internal friction depends on the heat treatment of the specimen and varies in the range 10 −6 to 3 × 10 −5. Moreover, the trend of the break away strain amplitude with heat treatment is the inverse of that for the trend of Young's modulus. 4. 4. When the internal friction data for 10 −5 ε −1 < 1 are analyzed in terms of the Granato-Lücke (GL) theory of dislocation damping, values of the minor loop length L c of the vibrating dislocation line and of the mobile dislocation density Λ could be extracted for the specimens. 5. 5. The values of L c (13 to 46 nm) and of Λ (10 10 to 10 12 m −2) obtained from the analysis are acceptable when interpreted in terms of TEM observations on carbide precipitates and dislocations in turbine blade materials similar to the material used in this study. 6. 6. The mobile dislocation density under conditions of amplitude dependent internal friction is less than the estimated total dislocation density. 7. 7. The internal friction results suggest that the value of K (the variable in the GL theory which depends on crystallographic orientation and specimen material) for the specimens used should be near 0.5, and that the value of L N (the major dislocation loop length) should be near 10 −7m.