Environmentally assisted embrittlement of ADI by contact with liquids

Abstract

Austempered ductile iron (ADI) suffers an uncommon embrittlement process when it is stressed above its yield strength in contact with water and other liquids. The advances in the understanding and characteristics of this environmentally assisted embrittlement process, since it was first reported, are summarised. The extent of embrittlement for different ADI strength grades is characterised. The influence of various liquid environments is discussed. The features of the fracture surfaces are also analysed. Recent results of testing under applied potential are presented. An explanation of the fracture mechanism is proposed, based on the recent identification of cracks which developed in the last to freeze portions as a result of plastic deformation.