STP651: Screening Test Method Development for Fracture Resistance Measurements in Thin-Gage Titanium

    Judy, RW
    Headhead, Engineering Materials Division, U. S. Naval Research Laboratory, Washington, D. C.

    Goode, RJ
    Headhead, Engineering Materials Division, U. S. Naval Research Laboratory, Washington, D. C.

    Pages: 11    Published: Jan 1978


    Abstract

    Titanium sheet products in gages less than 12.5 mm are used for many lightweight, highly efficient structures. Since these materials are very expensive, in many cases their use requires that very careful attention be given to the prevention of crack growth and fracture. One result of this design approach is that minimum allowable fracture resistance values are specified for mill products; screening tests for quality assurance are required to certify that these minimum values of fracture resistance are met for each sheet of material. The dynamic tear (DT) test was developed for this purpose for heavier section materials (16 mm and thicker) for steels, aluminum alloys, and titanium alloys. Correlations of DT energy values with linear-elastic fracture mechanics parameters enables the determination of KIc values on a routine basis by methods that are quicker and less expensive than direct measurement of KIc. Additionally, the DT test can be used to measure fracture resistance properties of materials in the elastic-plastic and plastic ranges, which is not possible by linear-elastic methods. Past studies of the effect of specimen dimensions on measured DT energy values have shown that the fracture resistance of materials can be expressed in terms of a constant Rp. Using the relationships developed for heavier section materials, a study involving several titanium alloys in thicknesses ranging from 2.5 to 12.7 mm showed that the fracture behavior of thin-section titanium alloys could be rationalized by these methods.

    Keywords:

    titanium, titanium alloys, fractures (materials), dynamic tests


    Paper ID: STP26545S

    Committee/Subcommittee: E08.07

    DOI: 10.1520/STP26545S


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