Gerçek deniz ortamında su altı kaynağı ile birleştirilen Grade AH36 gemi sacının kaynak bölgesinin karakterizasyonu

Abstract

Welding process at real underwater conditions  Weldability of Grade AH36 steel sheep plate at real underwater with different depths  Microstructural and mechanical properties of the welded joints Figure A. Flowchart of the study Purpose: The main aim of this study was to investigate weldability of low carbon Grade AH36 steel ship plate at the real marine conditions with different water depths. Theory and Methods: Grade AH36 steel ship plate frequently used for off shore applications was joined at both the atmospheric and real underwater conditions with different water depths through shielded metal arc welding process. The welded specimens firstly subjected to visual inspection and this was followed by the radiographic test. Microhardness, bending, impact toughness tests were also carried out in order to determine the mechanical properties of the joints. Microstructural examines were performed to examine the structural transformation on the weld zones. Results: Microstructural and mechanical properties of the welded specimens at both the atmospheric and real under water conditions were evaluated in detail. From the results of visual inspection test; some welding defects were seen on the samples joined at underwater. It was determined from the microhardness test; for all specimens, micro hardness values of the weld metal were lower than the HAZ and higher than the base metal. Samples joined under the atmospheric conditions has about 50% higher impact toughness value than the samples joined at underwater. Microstructural examines show that specimens joined underwater presented approximately 25-50% narrower HAZ than the specimens joined at atmospheric conditions. Conclusion: This study presents better understanding case of the welding process at real underwater conditions. The study also deals with weldability of Grade AH36 steel and comparison between atmospheric and real underwater conditions.