ANALYSIS OF COMPOSITIONAL EFFECTS ON FRACTURE AND STRESS CORROSION CRACKING PROPERTIES OF TITANIUM ALLOYS IN HEAVY SECTION SIZES

摘要

The objective of this research was to develop new alloy chemistries and thermo-mechanical processing in thick section sizes for marine application. The emphasis of the work was on maximizing fracture resistance at a given yield strength combinations, while maintaining high resistance to environmental effects. To support these programs, many large heats of alloys were fabricated as rolled plates in the 25-75 mm thickness range. These programs were part of a larger effort intended to establish procedures for using such materials in applications where high resistance to dynamic fracture was essential. It was established very early that maximum resistance to dynamic fracture in titanium alloys can only be attained by limiting oxygen content to levels below 0.10%, and that dynamic fracture properties can be tailored by alloy additions and modifying microstructural parameters. Static fracture properties, including parameters measured in stress corrosion cracking tests, depend on structure and composition to a higher degree. An analysis of the compositional effects on both static and dynamic fracture in heavy section titanium alloys is presented.