Effect of Material Property Difference on the Creep Behavior of Bending Specimen

Abstract

The application of small specimen testing techniques in the evaluation of creep properties of materials in-service arise. In order to acquire the creep data accurately and conveniently, the bending test with small beam specimens has been proposed and validated for the metal materials. Initially, the fact that material behaves different creep rates under tension and compression is ignored for simplification. Thus, the effect of material property difference on the creep behavior of bending specimen is analyzed in the present paper. On the basis of Norton creep law, the deformation behavior of three type’s specimens under tension and compression is theoretically described. Assumed different creep exponents and constants, finite element models of these beam bending specimens are established. The creep response is simulated. Meanwhile, the effect of material property under different stress state is further investigated. The results show that the stress exponent has a significant effect on the creep curves. Usually, the stress exponent can be evaluated based on the displacement rate or strain rate. However, if large discrepancy of creep properties under tension and compression exits, it will yield disparate results for the steady-state stress exponent. It is suggested that the stress exponent determined solely by bending test should be accepted with a certain degree of reliability, especially for the non-metal materials.