EUROPEAN CONCERTED ACTION COST 50. MATERIALS FOR GAS TURBINE
An approach has been made adopted to study the low cycle fatigue behaviour of PM Astroloy over a range of testing conditions (temperature, strain rate, plastic strain amplitude) which span the range from cycle dependent to time-dependent low cycle fatigue. It appears that both crack initiation and crack growth depend in a non-systematic manner on the testing parameters, which results from the simultaneous action of several time- dependent processes. These time-dependent processes cause Tomkins' crack growth model to fail to correctly predict the number of cycles spent in crack growth at the high temperature, low strain rate end of the test parameter spectrum. At the other end of the test parameter spectrum the match with the experimental data is fortuitious since the laws governing the crack growth behaviour for crack sizes below and beyond approximately 200 mum (short crack growth behaviour and higher order dependence of the crack growth rate on the crack depth, respectively) deviate from the crack growth law which is at the basis of Tomkins' model. The experimental crack increment data are used to compute fracture mechanics lives. It is suggested that these fracture mechanics lives are appropriate lower-bound estimates of the life of PM Astroloy containing defects such as inclusions.
Bibliographic Reference: EUR 8808 EN (1984) FS, 34 P., BFR 150, EUROFFICE, LUXEMBOURG POB 1003
Availability: Can be ordered online
Record Number: 1989122037100 / Last updated on: 1987-01-01
Available languages: en