The bone cement failed at the distal end of the prosthesis stem of femoral head prosthesis six months after implantation. A small indentation on the lateral contour of the stem was visible where the stem had broken. The degree of loosening (gap between the lateral stem contour and the bone or cement) and implant loading was revealed by the dislocation of fragments of the prosthesis. Secondary cracks that had originated at the lateral aspect of the stem were revealed by metallographic examination of a section parallel to the stem surface and perpendicular to the fracture surface of the distal fragment. Gas pores are apparent in the grain and at the grain boundaries were revealed by a transverse section. Fine parallel line structures that run diagonally through the fractograph may be slip traces were revealed by scanning electron microscopy. One of the cracks was revealed to have propagated through a larger gas pore by a ruptured gas pore. The stresses created through the fatigue process activated glide systems which served the formation of secondary cracks along glide planes.

One of 14 vertical radiant tubes (RA 333 alloy) in a heat-treating furnace failed when a hole about 5 x 12.5 cm (2 x 5 in.) corroded completely through the tube wall. The tube measured 183 cm (72 in.) in length and 8.9 cm (3 in.) in OD and had a wall thickness of about 3 mm (0.120 in.). Failure occurred where the tube passed through the refractory hearth (floor) of the furnace. Although the furnace atmosphere was neutral with respect to the work, it had a carburizing potential relative to the radiant tubes. Analysis (visual inspection, 250x spectroscopic examination of specimens etched with mixed acids, metallographic examination, and chemical analysis) supported the conclusions that the premature failure of the tube by perforation at the hearth level resulted from (1) corrosion caused by sulfur contamination from the refractory cement in contact with the tube and (2) severe local overheating at the same location. Recommendations included replacing all tubes using a low sulfur refractory cement in installation and controlling burner positioning and regulation more closely to avoid excessive heat input at the hearth level.

The Rocky Point Viaduct, located near Port Orford, OR, was replaced after only 40 years of service. A beam from the original viaduct was studied in detail to determine the mechanisms contributing to severe corrosion damage to the structure. Results are presented from the delamination survey, potential and corrosion mapping, concrete chemistry, and concrete physical properties. The major cause of corrosion damage appears to have been the presence of both pre-existing and environmentally-delivered chlorides in the concrete.

Forged aluminum alloy 2014-T6 hinge brackets in naval aircraft rudder and aileron linkages were found cracked in service. The cracks were in the hinge lugs, adjacent to a bushing made of cadmium-plated 4130 steel. Investigation (visual inspection and 250X micrographs) supported the conclusion that the failure of the hinge brackets occurred by SCC. The corrosion was caused by exposure to a marine environment in the absence of paint in stressed areas due to chipping. The stress resulted from the interference fit of the bushing in the lug hole. Recommendations included inspecting all hinge brackets in service for cracks and for proper maintenance of paint. Also suggested was replacing the aluminum alloy 2015-T6 with alloy 7075-T6, and surface treatment for the 7075-T6 brackets was recommended using sulfuric acid anodizing and dichromate sealing. Finally, it was also recommended that the interference fit of the bushing in the lug hole be discontinued.

A substantial number of copper alloy C27000 (yellow brass, 65Cu-35Zn) ferrules for electrical fuses cracked while in storage and while in service in paper mills and other chemical processing plants. The ferrules, made by three different manufacturers, were of several sizes. One commonly used ferrule was 3.5 cm long by 7.5 cm in diam and was drawn from 0.5 mm (0.020 in.) thick strip. Investigation (visual inspection, metallographic examination, and a mercurous nitrate test, which is an accelerated test used to detect residual stress in copper and copper alloys) of both ferrules from fuses in service and storage in different types of plants, and ferrules from newly manufactured fuses, supported the conclusion that the ferrules failed by SCC resulting from residual stresses induced during forming and the ambient atmospheres in the chemical plants. The atmosphere in the paper mills was the most detrimental, and the higher incidence of cracking of ferrules there was apparently related to a higher concentration of ammonia in conjunction with high humidity. Recommendations included specifying that the fuses meet the requirements of ASTM B 154.

Argonne National Laboratory has conducted analyses of failed components from nuclear power-generating stations since 1974. The considerations involved in working with and analyzing radioactive components are reviewed here, and the decontamination of these components is discussed. Analyses of four failed components from nuclear plants are then described to illustrate the kinds of failures seen in service. The failures discussed are (1) intergranular stress-corrosion cracking of core spray injection piping in a boiling water reactor, (2) failure of canopy seal welds in adapter tube assemblies in the control rod drive head of a pressurized water reactor, (3) thermal fatigue of a recirculation pump shaft in a boiling water reactor, and (4) failure of pump seal wear rings by nickel leaching in a boiling water reactor.

Several tin plated, low-alloy steel couplings designed to connect sections of 180 mm (7 in.) diam casing for application in a gas well fractured under normal operating conditions. The couplings were purchased to American Petroleum Institute (API) specifications for P-110 material. Chemical analysis and mechanical testing of the failed couplings showed that they had been manufactured to the API specification for Q-125, more stringent specification than P-110, and met all requirements of the application. Fractographic examination showed that the point of initiation was an embrittled region approximately 25 mm (1 in.) from the end of the coupling. The source of the embrittlement was determined to be hydrogen charging during tin plating. Changes in the plating process were recommended.

A detailed investigative failure analysis was conducted on an autoclave which blew apart in a furnace for no apparent reason. Bolt failure resulted in separation of the autoclave lid and subsequent destruction of the furnace. Analysis using metallography, fractography, mechanical testing and exemplar tests were performed on the bolt material. Mechanical engineering analysis and leak-before-break criteria were extensively analyzed. Results led to only one possible conclusion: that an explosion occurred within the autoclave. Suggestions for autoclave design are presented as a result of the analysis.

This article commences with a description of the prosthetic devices and implants used for internal fixation. It describes the complications related to implants and provides a list of major standards for orthopedic implant materials. The article illustrates the body environment and its interactions with implants. The considerations for designing internal fixation devices are also described. The article analyzes failed internal fixation devices by explaining the failures of implants and prosthetic devices due to implant deficiencies, mechanical or biomechanical conditions, and degradation. Finally, the article discusses the fatigue properties of implant materials and the fractures of total hip joint prostheses.

Total knee prostheses were retrieved from patients after radiographs revealed fracture of the Ti-6A1-4 VELI metal backing of the polyethylene tibial component. The components were analyzed using scanning electron microscopy. Porous coated and uncoated tibial trays were found to have failed by fatigue. Implants with porous coatings showed significant loss of the bead coating and subsequent migration of the beads to the articulating surface between the polyethylene tibial component and the femoral component, resulting in significant third-body wear and degradation of the polyethylene. The sintered porous coating exhibited multiple regions where fatigue fracture of the neck region occurred, as well as indications that the sintering process did not fully incorporate the beads onto the substrate. Better process control during sintering and use of subsequent heat treatments to ensure a bimodal microstructure were recommended.

A cast stainless steel femoral head replacement prosthesis fractured midway down the stem within 13 months of implantation. Visual examination showed severe “orange peel” around the fracture on the concave side. This effect was not observed on the convex side, which suggested fatigue fracture. Metallographic examination of samples revealed an extremely large grain size and corroborated fatigue fracture. Chemical analysis indicated that the material conformed to the requirements for type 316L stainless steel. Substandard-size tensile bars machined from another prosthesis from the same manufacturer showing identical grain sizes were used for mechanical testing. Tensile tests indicated that the material did not meet the manufacturer's stated strength criteria in the portion of the stem that fractured. The failure was attributed to low strength, which resulted in fatigue. The extremely coarse grain size was considered a major factor in strength reduction.