Effect of copper addition on the structure and mechanical properties of ST52 plain carbon steel weld metal made by GMAW method

In this study, the effect of adding copper element to the filler metal on the microstructure and mechanical properties of plain carbon welded metal welded by GMAW method was investigated. In order to carry out this research, the wires required for welding were prepared in raw form and after determining their chemical composition, they were coated with copper element in the factory during a process. Then, 5 pieces of plain carbon steel DIN ST52 in dimensions of 20 × 200 × 320 mm were selected as the base metal and welding operations were performed on the first piece with uncoated copper wire and on the other four pieces with plated wires containing 0.04, 0.09, 0.11 and 0.13% of copper. Welding was performed in seven layers and in two passes under the same conditions and under CO2 shielding gas. After welding, eye, penetrant, radiography, tensile, impact, microstructure and scanning electron microscopy tests and chemical composition tests were performed on the samples. The results of eye, penetrant and radiographic examinations showed no defects at the joint. The results of tensile test showed that with increasing the amount of copper to 0.04% in the wire coating, the tensile strength decreased and with increasing this amount to 0.13%, the tensile strength increased. Examination of the impact test results showed that with increasing the amount of copper to 0.04% in the wire coating, the amount of energy absorbed by the sample increased and with increasing this amount of copper decreased to 0.13% of the amount of energy absorbed by the sample. The results of microstructural study showed that adding 0.04% of copper to the welding wire caused needle ferrite. Increasing the amount of copper to 0.13% decreased the needle ferrite and increased the grain ferrite.

Keywords:

Copper - microstructure-structure-wires