COMPARISON OF LOW-CYCLE FATIGUE BEHAVIOR OF A LOW-CARBON STEEL AND ITS STAINLESS-CLAD BIMETALLIC STEEL

The stainless-clad bimetallic steel has attracted increasingly concern and application in civil engineering, but its mechanical properties under cyclic loading still demand deeper understanding. Through uniaxial tensile tests and low-cycle fatigue tests controlled by symmetrical strain loading, this paper has comparatively investigated the cyclic elastoplastic behavior and low-cycle fatigue life of the hot-rolling stainless-clad 304+Q235B bimetallic steel and its substrate layer Q235B carbon steel. Based on the finite element results of the cross-section stress distribution at different tensile strain levels in the fatigue specimens, the mechanical mechanism of the low-cycle fatigue failure mode in the bimetallic steel has been discussed. The results indicate that no interface debonding of the tested coupons occurs under both tensile and cyclic loading conditions. Cyclic hardening which is positively related to the applied strain amplitudes is observed in both the bimetallic steel and its Q235B carbon steel, but the bimetallic steel exhibits the higher maximum cyclic stress. The fatigue cracking always initiates in the side of the Q235B steel, which results from the combined effect of the different stress states and plastic deformation capacities. However, the experimental low-cycle fatigue life of the bimetallic steel is similar to that of the Q235 steel. This batch of 304+Q235B bimetallic steel exhibits qualified low-cycle fatigue performance, which can be used as an alternative for the Q235B carbon steel in engineering structural components demanding higher corrosion resistance. © 2024 Tsinghua University. All rights reserved.