TY - THES

T1 - Optimization of welding consumables for arc welding with flux cored wire electrodes

AU - Özcelik, Koray

N1 - embargoed until 28-05-2025

PY - 2020

Y1 - 2020

N2 - The generation of pockmarks are common in the arc welding process with flux cored wire electrodes under CO2 shielding gas atmosphere. Optimization of welding consumables such as new flux formulations is required in order to bring solution for this problem. In this research, the optimization of flux is studied by adding ZrO, FeSiTi, CaF2, Na3AlF6, and MnO. The quality level of weld bead is characterized by counting the number of pockmarks according to ISO 5817 Standard. Thermodynamically calculations and LECO test are used to evaluate the generation of N2 and O2 during welding. The results show that CaF2, Na3AlF6, and MnO give the sufficient quality of weld bead appearance regarding to pockmarks due to the influence on decreasing the solidification temperature and viscosities of slags, which give enough time for gases to escape from the weld pool. The optimization range for CaF2, Na3AlF6, and MnO additions are 2.5%, 5% and 5% respectively. MnO addition of 5% by mass into flux is supposed to be the best choice to optimize the welding flux in the rutile duplex flux cored electrode against pockmarks regarding to clean weld surface and less spattering formation. According to thermodynamic calculations, the formation of pockmarks may be caused by generation of CO, N2 and H2, which may be trapped due to higher slag viscosity.

AB - The generation of pockmarks are common in the arc welding process with flux cored wire electrodes under CO2 shielding gas atmosphere. Optimization of welding consumables such as new flux formulations is required in order to bring solution for this problem. In this research, the optimization of flux is studied by adding ZrO, FeSiTi, CaF2, Na3AlF6, and MnO. The quality level of weld bead is characterized by counting the number of pockmarks according to ISO 5817 Standard. Thermodynamically calculations and LECO test are used to evaluate the generation of N2 and O2 during welding. The results show that CaF2, Na3AlF6, and MnO give the sufficient quality of weld bead appearance regarding to pockmarks due to the influence on decreasing the solidification temperature and viscosities of slags, which give enough time for gases to escape from the weld pool. The optimization range for CaF2, Na3AlF6, and MnO additions are 2.5%, 5% and 5% respectively. MnO addition of 5% by mass into flux is supposed to be the best choice to optimize the welding flux in the rutile duplex flux cored electrode against pockmarks regarding to clean weld surface and less spattering formation. According to thermodynamic calculations, the formation of pockmarks may be caused by generation of CO, N2 and H2, which may be trapped due to higher slag viscosity.

KW - Schutzgasschweißen mit Fülldrahtelektroden

KW - pockmark

KW - Optimierung von Schweißflüssen

KW - Viskosität

KW - Flux cored arc welding

KW - pockmark

KW - flux optimization

KW - slag viscosity

M3 - Master's Thesis

ER -