This RS can be tractive or compressive depending on the constraints transmitted from the adjacent areas. Finally, during the cooling down process, the areas yielded at high temperature constrain the elastic springback of not yielded areas generating internal stresses that remain on the welded component. Thus, they also limit the expansion of adjacent areas at higher temperature which, in addition, present lower strength and, consequently, can suffer compressive plastic deformation. This way, the material at lower temperature suffers lower thermal expansion and presents higher strength. High thermal gradients generate inhomogeneous thermal expansion constrained by the surrounding material, which presents temperature-dependent mechanical properties. RS are generated due to high thermal cycles in the welding process where non-uniform heating and cooling occur. Nevertheless, one of the main drawbacks of welded structures is the generation of residual stresses (RS), which may compromise their mechanical performance. For this reason, spray transfer mode is especially adequate to join thick plate structures. ![]() Particularly, multipass welding in spray transfer mode presents uniform metal transfer to workpiece at high rate, together with high arc stability and low weld spatter. Gas metal arc welding (GMAW, also referred as metal inert gas (MIG)), is one of the most extended welding techniques in metal manufacturing industry. Finally, the proposed methodology is extended to analyse the influence of the thickness and the number of passes in the RS pattern of thick T-joint welds. The experimental validation of the methodology conducted for a multipass butt weld case shows good agreement in both the temperature pattern (9.16% deviation) and the RS pattern (42 MPa deviation). Alternatively, in this chapter, a new methodology to define the heat source energy based on the spray welding physics is exposed. However, the use of these methods during the design process is limited, as they require experimentally defining many parameters. Nowadays, there are different numerical methods to predict the RS generated in GMAW process, being Goldakās method one of the most widely used model. This fact is especially relevant in big structures since it generates high material, manufacturing and product transportation costs. Consequently, most of the currently used dimensioning approaches do not consider RS, leading to design oversized structures. ![]() Nevertheless, RS pattern prediction is complex and requires the simulation of the welding process. One of the main problems of gas metal arc welding (GMAW) process is the generation of residual stresses (RS), which has a direct impact on the mechanical performance of welded components.
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