Stress-corrosion cracking of nickel andhigh nickel alloys is rare but not unknown.As with other metals and alloys thisphenomenon, in the high nickel materials,is highly specific; it has occurred onlyunder exposure to certain fairly welldefined corrosive conditions and is not afunction of corrosion rate. It is not aserious hazard; the cases to be recountedare actually only isolated instances in theexperience of many years' use of manymillions of pounds of the high nickelmaterials in the services in which theisolated instances have occurred. Therehave been no cases in the experience ofthe major producer of nickel of spontaneouscracking of stressed material under atmosphericexposure, such as occurs withcertain copper-zinc alloys.