China
Africa
Explore chapters and articles related to this topic
Gas shielded arc welding (MIG, MAG and TIG)
Published in Andrew Livesey, Alan Robinson, The Repair of Vehicle Bodies, 2018
One of the important functions of the shielding gas is to protect the weld zone from the surrounding atmosphere and from the deleterious effects of oxygen, nitrogen and hydrogen upon the chemical composition and properties of the resulting weld. In this capacity the gas fulfils the major function of the fluxes used as electrode coverings or deposited as an enveloping layer during welding with other processes. The obvious advantages derived from the use of gas shielding are that the weld area is fully visible; that little, if any, slag is produced; and that the absence of abrasive flux increases the life of jigs and machine tools. In the MIG welding process, gas shielding enables a high degree of mechanism of welding to be achieved. Few gases possess the required shielding properties, however, and those that do with certainty – the inert gases, notably argon – are relatively expensive.
Chapter 1 Arc Welding Processes
Published in Svensson Lars-Erik, in Steel Arc Welds, 2017
This method is often called TIG (tungsten-inert gas). The shielding gases used are mainly argon or helium. With the use of inert gases, the weld metal becomes very clean and of high quality. The method is usually applied manually, but is capable of easily lending itself for mechanization. One typical application in the mechanized form is tube welding (Figure 1.9).
Effects of Performance Measures of Non-conventional Joining Processes on Mechanical Properties of Metal Matrix Composites
Published in Suneev Anil Bansal, Virat Khanna, Pallav Gupta, Metal Matrix Composites, 2023
Kamaljit Singh, Suneev Anil Bansal, Virat Khanna, Satinder Singh
Shielding gas selection should be made upon the basis of chemical and metallurgical phenomenon in between the gas and molten metal pool. A shielding gas can cause an adverse effect on the penetration, size, and efficiency of the weld. The fundamental purpose of shield gases is to ensure the weld area is well protected from oxidation, to maintain an accurate convection rate and to stabilize the plasma. Improper shielding can cause defects in the weld such as pores, undercut, and bead surface roughness, especially in the case of CO2 laser welding (Cao et al., 2003). Several gases such as helium, nitrogen, CO2, and argon have been used in different studies for this purpose. Gases which are dense like argon assist in penetration through mechanical exertion, whereas gases such as helium which are lighter have higher ionization potential and can absorb a large quantity of energy (Fotovvati et al., 2018). Moreover, the shielding gas distance and inclination angle from the laser material interface region also influence the occurrence of weld contamination (Meng et al., 2013b). Besides this, gas flow rate is another important aspect that results in improved weld properties. Shielding gas reduces the temperature of the workpiece during the welding operation. The CFD (computational fluid dynamics) analysis of laser welding process under the influence of shielding gas asserts that the cooling process during solidification improves when the gas flow rate is high. At low gas glow rate numerous defects such as spattering, irregularities in weld, and sagging could emerge on the weld bead surface (Bannour et al., 2012; Vyskoč et al., 2020).
Experimental evaluation of longitudinal tensile properties of ferritic stainless-steel weldment joined by metal inert gas, pulse metal inert gas, and tungsten inert gas welding
Published in Welding International, 2022
Shahid Hussain, Ajai Kumar Pathak
MIG welding is also known as gas metal arc welding (GMAW). In this process, an arc is produced between a continuously feeding electrode wire and a workpiece. The molten weld pool and electric arc are protected through shielding gases. Based on welding conditions and workpiece material, the shielding gas may be selected as helium, argon, nitrogen, or their mixture [9]. In MIG welding, due to arc instability, pure argon as a shielding gas is not preferred. Argon with 2% carbon dioxide or 2% oxygen may be employed for the welding of FSS base materials to overcome this problem of arc instability [10]. The molten metal from the consumable electrode tip may be transferred to the weld pool through three fundamental transfer techniques, namely spray, globular, and short-circuit. MIG welding setup provides deep penetration, high welding speed, and high heat input [11].