Calorimetric analyses of the comprehensive heat flow for gas metal arc welding

Abstract

Within this manuscript, the comprehensive heat flow, as well as the energy balance for gas-shielded arc welding processes based on experimental investigations is discussed. The main focus lies on the gas metal arc welding (GMAW) process which is further analysed. Different calorimetric measurement methods and results for the separate determination of the energy content of droplet and welding arc as well as energy input into the component are presented. Additionally, heat losses to the surrounding atmosphere and the cooling energy of the external cooling power source system are analysed. The mean droplet temperatures are within a range of T _dr = 2,350 … 2,700 °C. The studies also show that a specific manipulation of the droplet temperature during the welding process is not possible and droplet temperature depends on several parameters. Increasing the wire feed speed, reducing the diameter of the filler material or increasing the stick out length result in an increase of the droplet temperature. The analyses allow to conclude that the welding arc is mainly responsible for the weld seam penetration and the droplet temperature only contributes in a minor manner. Preliminary experiments also show that the heat input into the component is highly influenced by the selection of welding parameters. Measurements confirm that it is possible to increase the efficiency of welding processes for example by reducing the wire feed speed, using carbon dioxide shielding gas or increasing the stick out length. On the contrary, increasing the current or voltage or reducing the shielding gas flow reduces the process efficiency. The difference between the lowest and highest achievable value of efficiency can be more than 15 % for one specific welding process.