With the advent of the 80's there has been an increasing need for analytic and numerical techniques, based on a thorough understanding of microstructural processes, that express in a manner suitable for practicing engineers the reliability of components and structures that are being subjected to degradation situations. Such situations fall within the framework offracture mechanics, fatigue, corrosion fatigue and pitting corrosion. Luckily, such techniques are now being developed and it was felt timely to combine in one volume reports by the leaders in this field who are currently making great strides towards solving these problems. Hence the idea of this monograph was born and I am pleased to be associated both with it and the contributors whose chapters are included in this volume. A very large part of the credit for this monograph must go to the authors who have taken time out from their busy schedules to prepare their submissions. They have all worked diligently over the last few months in order to get their manuscripts to me on time and I sincerely thank them for their help throughout the preparation of this volume.