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Influence of welding parameters on weld quality and productivity using metal cored wires

Stavros Kotsakis ; Kimon Drosos
Göteborg : Chalmers tekniska högskola, 2014. 60 s. Diploma work - Department of Materials and Manufacturing Technology, Chalmers University of Technology, 2014.
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Robotic Gas Metal Arc Welding (GMAW) is used in fatigue loaded structures where demands on weld quality are very high. Bead dimensions of a weld such as penetration bead thickness and toe radius can reveal whether a weld can reach high fatigue life. However, several welding parameters have high impact on these dimensions. From previous research it has been indicated that geometrical parameters such as torch angle, weld position, push or pull direction etc. are the most influential ones concerning quality of a weld with solid wires. Welding technology offers solid or metal cored wires for robotic GMAW. Even though metal cored wires depict several advantages compared to solid, a lot of skepticism is faced among industries due to its higher cost. Response parameters of a fillet weld by robotized GMAW using metal cored wire were investigated as a function of welding geometry parameters. The goal is to reveal the optimal settings aiming at as high productivity as possible. Iteration of welding tests using solid wire has been made in order to depict repeatability of previous test results with the same settings. Next step consisted of several series of experiments varying geometrical parameters using metal cored electrode. Repetition of this series for different values of wire feed rate has been carried out and comparisons are made. In order to reveal higher possible productivity, a few tests were carried out for the optimal welds from previous steps for different welding speeds and with pulsed welding. Specimens were cut, grinded and etched. Measurement of weld dimensions was performed via Lumenera software. Analysis of the results was made with JMP 11 software by SAS. Results indicated that for metal cored wire the majority of high quality welds were performed in push direction, PA position and gun angle of 35o. Correlation analysis showed the nature of the relationships between input and output parameters. Prediction models were constructed for all weld dimensions using regression analysis. Tests with higher welding speeds suggest that there are possibilities for productivity improvement. Pulsed welding revealed that only a trade-off between values of bead thickness and penetration can create a quality weld. Less total amount of high quality welds are observed in pulsed welding, in comparison with conventional welding.

Nyckelord: fatigue loaded structures, GMAW, solid wire, metal cored wire, weld quality, bead geometry, welding geometry parameters, regression analysis, optimization, modeling, pulsed welding.



Publikationen registrerades 2016-07-07. Den ändrades senast 2016-07-07

CPL ID: 239128

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