An alternative method of decreasing Delta K FCGR testing

The conventional technique of decreasing Delta K FCGR testing often present s experimental difficulties in terms of the length of crack that must. be a ccommodated and the time required to reach low values of Delta K. Addressin g these issues, an alternative method of conducting such tests has been pro posed. A relation according to which Delta K must be decreased has been der ived assuming that the monotonic plastic zone size can be decreased at a co nstant rate with increase in crack length without adversely affecting the i ntegrity of the FCGR data. Through experimental assessment of the alternati ve method and examination of crack closure effects, such an asumption has b een vindicated. it has been shown that this method is particularly suitable for high strength materials and that it provides: great advantages when co nducting FCGR tests at low frequencies. The employment of the method for ob taining threshold regime corrosion fatigue crack growth data has been demon strated for HSLA steels. (C) 2000 Elsevier Science Ltd. All rights reserved .