Issue 42

D. Rozunmek et alii, Frattura ed Integrità Strutturale, 42 (2017) 40-45; DOI: 10.3221/IGF-ESIS.42.05 40 Focused on Mechanical Fatigue of Metals Crack growth of explosive welding zirconium-steel bimetal subjected to cyclic bending D. Rozumek, Z. Marciniak Opole University of Technology, Poland d.rozumek@po.opole.pl, z.marciniak@po.opole.pl A BSTRACT . The paper presents the fatigue test results including the cracks growth in the composite zirconium-steel subjected to oscillatory bending. Specimens of square cross-section without melted layer and with a melted layer were tested. In the specimens the net ratio of thickness of steel to zirconium layers was h 1 : h 2 = 2.5 : 1. It was observed that a higher fraction of the intermetallic inclusions near the interface increase the fatigue life. Two different interaction mechanisms between a crack and interface were observed. K EYWORDS . Explosive welding; Bending; Fatigue crack growth; Joint. Citation: Rozumek, D., Marciniak, Z., Crack growth of explosive welding zirconium-steel bimetal subjected to cyclic bending, Frattura ed Integrità Strutturale, 42 (2017) 40-45. Received: 31.05.2017 Accepted: 07.06.2017 Published: 01.10.2017 Copyright: © 2017 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION odern equipment in key branches of industry, like power industry, requires reliable structures. One of the most important element of the construction is the selection of the suitable material, whose task is to ensure durability in an aggressive environment [1]. However, the cost of the production of the working machines is getting significantly higher due to the material price. In order to lower the costs of the materials that are resistant to corrosion and durable in an aggressive environment, there are being created composites combining, for example, titanium or zirconium with steel obtaining the material with the demanding properties [2, 3]. Since the differences in mechanical properties of the materials are big, there are some issues with combining them. One method of bonding those kinds of materials is explosive welding. In which the base plate (steel) and the clad plate are set in specified distance called stand-off distance. The distance between both plates before joining is selected to assure suitable collision velocity. Parameters of the detonation system must ensure a suitable detonation velocity and a required amount of energy necessary for the sheet joining [4-7]. The explosive material is uniformly distributed on all the zirconium (titanium) sheet surface [7]. If the joined plates are parallel, the collision velocity is equal to the detonation velocity and equals from 2000 to 3500 m/s, depending on the joined metals. The stand-off distance between the sheets is dependent on the joined materials, their physical and mechanical properties and properties of the applied explosive material. The detonation velocity and the distance are the main parameters of the detonation system influencing a high quality of the obtained joint. The detonation velocity depends on a kind and amount of the applied explosive material per unit surface. This velocity should allow to obtain the M