Wear on a titanium screw head with a lip of material that that was transported by fretting at a plate-hole edge was studied. A flat fretting zone was visible on the screw surface over the material lip. A cellular wear structure containing wear debris was found. No morphological signs of corrosion were observed in connection with fretting structures.

This paper summarizes several cases of metallurgical failure analysis of surgical implants conducted at the Laboratory of Failure Analysis of IPT, in Brazil. Investigation revealed that most of the samples were not in accordance with ISO standards and presented evidence of corrosion assisted fracture. Additionally, some components were found to contain fabrication/processing defects that contributed to premature failure. The implant of nonbiocompatible materials results in immeasurable damage to patients as well as losses for the public investment. It is proposed that local sanitary regulation agencies create mechanisms to avoid commercialization of surgical implants that are not in accordance with standards and adopt the practice of retrieval analysis of failed implants. This would protect the public health by identifying and preventing the main causes of failure in surgical implants.

Brief overheating of the 89 mm OD 6.4 mm wall thickness titanium heater tubes (ASTM B337, grade 2) was caused by a flow stoppage in a leach heater. Blue-tinted areas and patches of flaky white, yellow, and brown oxide scale was revealed on visual examination. It was disclosed by subjecting the overheated tube to a flattening test that the tube no longer met ASTM B 337 specifications. Large grain size and numerous needlelike hydride particles were disclosed in the microstructure of the overheated tube. Heating to approximately 815 deg C was revealed by the presence of the flaky oxide and increased grain size. Hydrogen and oxygen absorption was revealed by the presence of hydrides and the shallow surface embrittlement and thus susceptibility to cracking at ambient temperatures was observed. It was concluded that the titanium tubes were embrittled due to overheating the tubes and the severe surface embrittlement resulted from oxygen absorption which made the surface layers susceptible to cracking under start up and shutdown. Replacement tubes made of a heat-resistant alloy (e.g., Hastelloy C-276) were recommended.