Copper electrical feedthrough pins used in a bolting application in a refrigeration compressor had functioned without failure for years of production and thousands of units. When some of the pins began to fail, an investigation was conducted to determine the cause. Visual examination revealed that the observed fractures were mixed brittle intergranular with ductile microvoid dimples. An extensive analysis of failed samples combined with a process of elimination indicated that the fractures were due to stress-corrosion cracking caused by an unidentified chemical species within the sealed compressor chamber. A unique combination of applied stress, residual stress, stress riser, and grain size helped isolate the failure mechanism to a single production lot of material.

A locomotive type boiler was fitted with a copper firebox of orthodox construction. Flanged tube- and firehole-plates were attached to a wrapper plate by means of copper rivets. Shortly after it was put into service the fireside heads of a number of rivets broke off at different parts of the seams. By the time the investigation was begun a total of fifty heads had broken off. Repairs had been effected from time to time by fitting screwed rivets, none of which gave trouble in service. Microscopic examination confirmed the fracture path to be wholly intergranular. In the region of the fracture the grain boundaries were delineated as a near-continuous network of cavities and films of oxide. It was evident that the failure of the rivets in service was attributable to intergranular weakness in the material due to gassing.