Arc welding

About: Arc welding is a research topic. Over the lifetime, 25393 publications have been published within this topic receiving 168182 citations.

Temperature and emissivity determination of liquid steel S235

Abstract: Temperature determination of liquid metals is difficult but a necessary tool for improving materials and processes such as arc welding in the metal-working industry. A method to determine the surface temperature of the weld pool is described. A TIG welding process and absolute calibrated optical emission spectroscopy are used. This method is combined with high-speed photography. 2D temperature profiles are obtained. The emissivity of the radiating surface has an important influence on the temperature determination. A temperature dependent emissivity for liquid steel is given for the spectral region between 650 and 850 nm.

Numerical Modeling of Enhanced Nitrogen Dissolution during Gas Tungsten Arc Welding

Abstract: Weld-metal nitrogen concentrations far in excess of Sieverts-law calculations during gas tungsten arc (GTA) welding of iron are investigated both experimentally and theoretically. A transient, threedimensional mathematical model has been developed to calculate the residual nitrogen concentrations during GTA welding. This model combines calculations for the plasma phase with those for nitrogen absorption and for the transport of nitrogen by convection and diffusion in the weld metal and diffusion throughout the weldment. In addition, the model takes into account the roles of turbulence and the nitrogen desorption reaction in affecting the residual nitrogen concentration in the weldment. Autogeneous GTA welding experiments in pure iron have been performed and the resulting nitrogen concentrations compared with the modeling results. Both experimental and modeled nitrogen concentrations fall in a range between 2.7 and 4.7 times higher than Sieverts-law calculations at a temperature of 2000 K. Modeled nitrogen concentrations correlate well with the experimental results, both in magnitude and in the general trends, with changes in the travel speed and nitrogen addition to the shielding gas.

Welding Stability System and Method

Abstract: A weld stability system for an arc welding apparatus and method of operation is disclosed. The weld stability system may comprise a shielding gas supply and a control assembly. The shielding gas supply may include a first source of gas, a second source of gas, a mixing chamber, a first valve selectively connecting the first source of gas to the mixing chamber, a second valve selectively connecting the second source of gas to the mixing chamber, and a shielding gas supply line configured to direct gas from the mixing chamber to a weld gun. The control assembly may include a controller operatively engaging the first and second valves, and at least one sensor configured to monitor a parameter of an arc welding process and communicate with the controller.

A real-time prediction model of electrode extension for GMAW

Abstract: This paper presents the development of an electrode extension model for the gas metal arc welding process based on the process voltage. The full dynamic model for the electrode extension is derived by combining a dynamic resistivity model with the voltage model. The electrode extension model was found to be represented mathematically by a nonlinear, time-varying, second-order ordinary differential equation. This model can be used in through-the-arc sensing and arc length control systems. To experimentally verify the model, the process dynamics were excited by a continuous sinusoidal variation of arc current. Using a constant current power source with the electrode positive, sinusoidal perturbations of variable amplitude were superimposed on the current to allow direct measurement of changes in electrode extension, arc length, and total voltage. A high-speed video system was used to capture the experimental electrode extension dynamics. The model was verified by comparing the frequency response of the model to the frequency response of the real process. Agreement between the simulations and the experimental results was found to be very good. The accuracy of this model was found to be approximately /spl plusmn/0.6 mm, which is considered to be suitable for process control applications.