| Abstract: | Contribution to the problem of stress corrosion cracking of austenitic steels It is shown on the basis of a stress corrosion cracking theories that the incubation phase is the factor determining the useful life of an element because in this phase protective layers are destroyed and crack nuclei are formed. Testing corrosion susceptibility in boiling magnesium chloride solution has the shortcoming that the solution is highly aggressive so that minor changes of the surface condition which may yield a considerable improvement of material behaviour in less aggressive conditions do not come to bear. Another shortcoming of MgC12 testing are divergent literature data concerning concentration so that there is also a scatter of boiling temperatures which has a pronounced influence on test results. Likewise an important role can be attributed to foreign ions and silicates from glas in the solution. It is more advantageous to use less concentrated solutions (up to 35%) because they enable clear current density potential curve to be obtained. An important factor concerning the test method is the previous investigation of specimens with a view to a residual stresses due to cold reduction. Under certain conditions the time to failure may be longer under cycling loads. |
