Prediction of long-term stress intensity limit of high-temperature creep structures

In order to predict stress intensity limit of high-temperature creep structures, creep work-time equation, defined as Wctp = B, was used, and the results of the equation were compared with Isochronous Stress-Strain Curve (ISSC) ones of ASME BPV NH code. For this purpose, the creep strain tests with time variations for commercial type 316 stainless steel were conducted with different stresses; 160 MPa, 150 MPa, 145 MPa, 140 MPa and 135 MPa at 593 .deg. C. The results of log Wc and log t plots showed a good linear relation up to 105 hr. The constants p, B and stress intensity limit values showed comparatively good agreement to those of ASME NH ISSC. It is believed that the relation can be simply obtained with only several short-term 1% strain data without ISSC which can be obtained by long-term creep data