The hole drilling method was used to determine residual stresses in bimetallic composite manufactured by explosive welding process. The analyzed bimetal consist of titanium Grade 1 (6 mm) and S355J2+N steel (40 mm). The aim of the paper is to establish the influence of the heat treatment on residual stress state in titanium layer. Residual stress calculations were performed according to standards developed by strain gauge manufacturer (TML) and ASTM standards. The main conclusion is the heat treatment considerably changes the residual stress state in titanium layer from tensile stress state (no heat treatment) to compression stress state (after the heat treatment).Keywords: explosive welding, residual stresses, bimetallic composite, titanium grade 1 W pracy przedstawiono wyniki badań naprężeń resztkowych, wyznaczonych metodą nawiercania, w bimetalu stal-tytan otrzymanego w procesie zgrzewania wybuchowego. Analizowany bimetal to kompozyt stali S355J2+N (40 mm) oraz tytanu Grade 1 (6 mm). Celem badania było ustalenie wpływu obróbki cieplnej na kierunki i wartości naprężeń własnych w warstwie tytanu. Obliczenia naprężeń resztkowych przeprowadzono przy zastosowaniu: (i) procedury zalecanej przez producenta (TML) zastosowanych rozet tensometrycznych oraz (ii) zaleceń ASTM (American Society for Testing and Materials). W wyniku badań ustalono, że zastosowana obróbka cieplna bimetalu zasadniczo zmienia stan naprężeń własnych w warstwie tytanu. Próbki bez obróbki cieplnej wykazują naprężenia resztkowe rozciągające a w próbkach po obróbce cieplnej panują naprężenia ściskające.
The aim of the research was to evaluate the changes in the surface properties of five functional clothing materials with water-repellent finishes (including PFC-free finish) after 1, 5, and 10 washes with three detergents. A new approach to the interpretation of the water-repellent properties of textile materials is presented, based on two techniques, i.e., the spray test method and contact angle measurements. The results showed that washing materials with hydrophobic finishes can cause significant changes in their properties, which are mainly dependent on the composition and structure of the material, as well as the type of hydrophobic finish. The PFC-free finish is the least resistant to washing. For all materials with PFC finishes, the water repellency depends on the fluorine content on the surface and fabric topography. It was also found that increasing washing frequency resulted in a gradual decrease in water repellency. The loss of water repellency below an acceptable level (Grade 3) occurred after the fifth washing for all materials. Significant differences in the interpretation of the results of the spray test and contact angle measurements were observed. Using these methods separately provides information on the changes in the surface properties of the tested materials; however, their parallel application allows for obtaining complementary data, which is important for the proper interpretation of results.
The main aim of the paper is determination of residual stresses in explosively welded steel-titanium bimetal. The analysis considers two bimetallic specimens: before and after the heat treatment. In residual stress determination the hole drilling method along with finite element analysis were applied. The results show different residual stress states depending on the heat treatment. The obtained results are confirmed by thermal stress calculation.
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