SAGBO on Inner and Outer Surface of Large Alloy 800H Pipe

Abstract One of the objectives of this series of case studies presented in section Failure Analysis of Practical Metallography is to educate colleagues who are new in the field, to inform them about failure mechanisms, not least about the rarer, more exotic ones and about metallurgical causes of failure that were utterly unexpected to occur in the particular failure case studies presented here. The subject of this contribution is a failure mechanism called Strain-assisted Grain Boundary Oxidation (SAGBO). This failure mechanism is not rare at all in hot-going nickel-base components in the aerospace industries. However, SAGBO was certainly unexpected to occur in large pipes that remained well below 400 °C in service.