Fundamental and Practical Aspects of Crack Growth under Corrosion Fatigue Conditions

Abstract

The crack growth mechanism is dependent on environment, frequency and temperature as shown by some examples. Two cracking modes are observed in aluminium alloys: the tensile mode and the shear mode. Examples show that inert environments promote the shear mode whereas aggressive environments promote the tensile mode. Information from constant-amplitude tests need not be applicable to service loading conditions as illustrated by an example. Significant environmental effects on crack growths are observed in aircraft flight-simulation tests. Growth delays induced by severe flights occur in all environments. As a consequence the truncation of the load spectrum at the high level end is a difficult question. The problem of producing relevant information in the laboratory is discussed.