Influence of lack of fusion on the fatigue life of welded joints in ship hull structures

   The paper is devoted to the study of the effect of lack of fusion on the fatigue strength of shipbuilding steel, since welding plays a major role in the formation of joints of steel structures in shipbuilding and ship repair.

   It is noted that during inspection, the technical condition of the vessel and its compliance with safety requirements are assessed.

   The relevance of the study is due to the fact that during inspection of hull elements, especially welded joints, defects characterized by a violation of the continuity of the weld metal are often detected, while their parameters exceed the limits established by regulatory documents.

   It is emphasized that when permissible limits are exceeded, defects must be removed in accordance with the shipyard technology, and the welds must be redone.

   The study considers the effect of lack of fusion on the serviceability of welded joints under rotating bending conditions. An analysis of studies addressing the influence of defects on welded joints is carried out. The results of experimental studies of the effect of lack of fusion in welded joints on fatigue strength are presented. Shipbuilding steel RSD40 was used as the material for the experiments. For fatigue testing, specimens were manufactured in accordance with GOST 25.502–79. The specimen loading scheme and the type of fatigue test are presented. Statistical processing of the test results was performed using the Minitab 18.1 software package. Dependences of fatigue life on stress amplitude were obtained. A comparative analysis of the fatigue strength of welded joints containing lack-of-fusion defects of different sizes under various stress amplitudes was carried out.

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