Recording of elevated temperature fatigue crack growth data by DCPD system

The growth of "long" fatigue cracks, in alpha-beta titanium alloy forging, subjected to cyclic stresses, is studied in this paper. The fatigue crack g rowth rate (FCGR) data were recorded at room temperature, 350, 450, 550 and 650 degrees F using the Direct Current Potential Difference (DCPD) techniq ue. The DCPD method, used in this investigation, was found to record and co rrelate the potential difference in terms of crack growth rate (da/dN) and Mode I stress intensity factor range satisfactorily. Various factors relate d to error minimization and calibration equations for compact tension speci mens have been elaborated. Also discussed were the means to enhance the acc uracy of the data by the DCPD system for elevated temperature fatigue crack growth rate testing.