Research on high-cycle fatigue properties of hot rolled titanium-clad bimetallic steel with low bonding strength

To study the high cycle fatigue properties of titanium-clad (TC) bimetallic steel, axial high cycle fatigue tests were carried out on TC bimetallic steel (TA2+Q355) plate produced by the hot rolling process with a thickness of 2 mm+8 mm. The basic mechanical properties were obtained by the tensile coupon tests and bonding interface shear tests. Based on the test results, the fatigue S-N curve of TC bimetallic steel at a stress ratio of 0.1 was obtained, which was compared with the fatigue design curves of traditional steel structures in four steel structure design specifications. The experimental results show that the tensile performance of TC bimetallic steels studied in this paper has three-stage fracture mode during tensile coupon test. In addition, although the shear strength of the bonding interface obtained by the shear tests is low, the fatigue performance of TC bimetallic steels is much higher than that of common single-metal structural steels, and it is conservative to predict the fatigue life of TC bimetallic steel by using the fatigue design curves of existing structural steel. Besides, the ratio of fatigue limit to tensile strength is 0.7, which is between those of titanium and steel. The low bonding strength makes the interface and the surface of the structural steel easy to become the fatigue sources of fatigue test, resulting in two different fatigue failure modes. Finally, the S-N curve suitable for this kind of TC bimetallic steel was presented. The research results can provide a reference for the fatigue design of TC bimetallic steel in the field of structural engineering, and promote its engineering application. © 2022, Editorial Office of Journal of Building Structures. All right reserved.