Effect of electrode heating on weld metal chemistry control in shielded metal arc welding
- Colorado School of Mines, Golden, CO (United States)
During welding with the shielded metal arc welding (SMAW) process, the electrode experiences an increase in temperature because of Joule heating and the heat from the arc conducted though the molten droplet to the solid wire. Heating of the electrode and temperature distribution along the electrode length will depend on the welding parameters as well as the ingredients of the flux coating. Thermal properties such as heat capacity and dissociation temperature of these ingredients can affect the heat transport through the electrode. A mathematical model taking into consideration the heat transport conditions in the electrode nd carbonate decomposition in the flux coating was developed to better understand and predict the increase in temperature in the core rod and coating of the electrode. Knowing the welding parameters and the physical properties of the flux ingredients, it was possible to estimate the temperature distribution along the length of the electrode, the location along the electrode length, above the arc where ingredients such as CaCO{sub 3} will start to dissociate and the oxygen potential of the shielding gas generated. To validate the model, the temperature of the core rod and the coating were monitored during actual welding. Experimental E7018 type electrodes with varying carbonate content were used. The remarkable conclusion of this research is that the stability of the flux ingredients and the welding parameters can be used to predict the thermal history along the electrode length and the oxygen potential in the arc environment during welding. The proposed mathematical model and thermodynamic data of the flux ingredients make it possible to control the chemical composition along the weld length.
- OSTI ID:
- 115502
- Report Number(s):
- CONF-9404233-; TRN: 95:002927-0080
- Resource Relation:
- Conference: 75. American Welding Society (AWS) annual meeting, Philadelphia, PA (United States), 10-15 Apr 1994; Other Information: PBD: 1994; Related Information: Is Part Of 75th Diamond anniversary American Welding Society annual meeting; PB: 273 p.
- Country of Publication:
- United States
- Language:
- English
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