Yazar "Colak, Zahit" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • Küçük Resim Yok
    Öğe
    Characterization of the weld zone of Grade AH36 steel ship plate joined at the real marine conditions through underwater welding
    (Gazi Univ, Fac Engineering Architecture, 2020) Colak, Zahit; Ayan, Yusuf; Kahraman, Nizamettin
    In this study, Grade AH36 steel ship plate was joined at both the atmospheric and real underwater conditions at ascending different depths through shielded metal arc welding process. The isolated E6013 rutile electrode was used in welding process. The welded specimens firstly subjected to visual inspection and this was followed by radiographic test. Bending and impact toughness tests were also carried out in order to determine the mechanical properties of the welded joints. Microstructural examines were performed to observe the structural transformation and hardness test was also conducted on the weld zones. Non-destructive test results showed that the specimens joined underwater had weld defect such as slag remains on the weld surface and between the pass, gas porosities, grooves and the lack of penetration. According to the bending test results, when the difference of water depth increased, the tests resulted in adversely at some angles due to defects like remains, gas porosities etc. on the weld metal. With respect to impact toughness tests, the specimens welded at atmospheric conditions presented better toughness than the others. The maximum hardness value was measured from the weld metal and this was followed by the heat affected zone (HAZ) and base metal sequentially. Microstructure evolutions showed that structures of the weld metals were dendritic, rolled structure of the base metal in the HAZ was destroyed and partial grains growth was seen in this section.
  • Küçük Resim Yok
    Öğe
    Weld morphology and mechanical performance of marine structural steel welded underwater in a real marine environment
    (Springer London Ltd, 2020) Colak, Zahit; Ayan, Yusuf; Kahraman, Nizamettin
    Grade AH36 ship steel plate, frequently used in offshore applications, was joined underwater by shielded metal arc welding (SMAW) using two different types of electrodes (E6013 and E7014). The ship steel plate was also joined under atmospheric conditions in order to compare both joints in terms of mechanical and metallurgical properties. The E6013 rutile electrode was isolated by wrapping before use, and the underwater welding process was carried out at a depth of 8 m under the sea. The joints were first subjected to visual inspection and then liquid penetrant, ultrasonic, and radiographic tests were performed. In order to determine the mechanical properties of the joints, tensile, bending, and impact toughness tests were also carried out. In addition to the microhardness test on the weld zones, microstructural examination was also performed on the joints. As a result of the nondestructive tests, weld defects like slag remaining between the passes, gas porosities, burn-through, and lack of penetration were seen on the joints welded underwater with the two different electrodes. The study determined that these defects had significantly influenced the mechanical properties and width of the weld zone of the joints.