DIAMETRAL LOW-CYCLE FATIGUE TESTING A COMPARISON OF FIRST EXPERIMENTAL RESULTS FROM DIAMETRAL LOW-CYCLE FATIGUE TESTS WITH RESULTS FROM AXIAL TESTS

摘要

The first experimental results of diametral low-cycle fatigue tests on DIN 1.4948 (similar to AISI type 304) at 823 K are reported. The cyclic hardening behaviour of diametral tests and axial tests only differs for the first (ten) cycles. Due to progressive strain hardening this difference reduces at increasing number of cycles. The cyclic stresses of diametral and axial tests are equal after cyclic hardening to values of about twice the 0.2 yield stress or higher. At low strain ranges ( delta epsilonsub(t) < 1.0%) the number of cycles to failure (Nsub(f)) of diametral tests on hour-glass specimens do not differ from those of axial tests on the uniform gauge length type (GRIM) specimen. At high strain ranges ( delta epsilonsub(t) < 1.0%) Nsub(f)-values of diametral tests are higher. This is attributed to the hour-glass shape of the specimen which allows high compressive stresses without buckling. (Atomindex citation 10:423244)