Interpretations of fracture toughness characteristics, as measured by various test procedures, for solutions of general engineering problems, are presented for structural titanium alloys. Analytical procedures evolved from fracture mechanics theory are used for quantitative interpretations of engineering fracture toughness tests. The procedural simplicity of the engineering tests coupled with the analytical capabilities of fracture mechanics theory provides for a significant advancement in failure-safe design procedures for titanium alloys covering the full range of strength levels.

Interpretative procedures are evolved from correlations of KIc with Dynamic Tear (DT) and Charpy-V notch (Cv) energy. An Optimum Material Trend Line (OMTL) diagram is developed for titanium alloys which summarizes all the DT fracture toughness data and is additionally indexed according to the KIc and Cv, correlation plots. OMTL limit curves are shown for the best and normally expected grades of material for the strength level.

Flaw size-stress calculations for fracture of 1- and 3-in. thick sections are overlaid to the OMTL diagram in the form of iso-flaw depth lines. KIc/σys ratio lines are indexed to the iso-flaw depth lines and a KIc/σys Ratio Analysis Diagram (RAD) is evolved. The RAD provides for a simplified, general engineering interpretation of flaw size/stress conditions for fracture.

The general fracture toughness characteristics of some principal titanium alloys are simply defined by zones in the RAD. A compendium of such zones provides a general understanding of the potentials for each generic class of titanium alloys.