High-cycle fatigue properties of explosion bonded titanium-clad bimetallic steel

Abstract

Titanium-clad (TC) bimetallic steel is a new type of high-performance laminated structural steel, of which the high-cycle fatigue properties were experimentally studied in this paper. The test coupons were manufactured from explosion bonded TA2 + Q355B TC bimetallic steel plate, and their fracture features after fatigue failure were analysed through a sets of scanning electron microscope (SEM) micrographs. Besides, their basic mechanical properties were obtained by the tensile coupon tests and bonding interface shear tests. Based on the test results, the fatigue stress-life curve (S–N curve) of the explosion bonded TC bimetallic steel was obtained, and it was subsequently compared with that of the uniform material law estimates as well as the codified S–N curves provided by four national standards for steel structure design. It demonstrates that the fatigue performance of TC bimetallic steel studied in this paper is much higher than that of standard single-metal structural steel (by over 20 % compared with the low-alloyed steels with similar tensile strength), and the fatigue design curves for conventional structural steel are conservative in predicting the fatigue life of the TC bimetallic steel herein. In addition, fatigue cracks tend to initiate from the bonding interface and exhibit considerably different propagation phenomena in the cladding titanium alloy and substrate structural steel regions.