This work is distinguished by searching for a non-destructive technology, and X-ray diffraction was validated by the XStress 3000 analyser. Measurements of residual stresses in the welded zone of premium pearlitic rails was performed, rail surface hardness of 370 HB and 0.79% carbon content. The welding of the rails was done by flash butt process, performed by Schlatter GAAS 80 stationary equipment. The results of the tensile and compressive stress measurements identified the residual stresses in the welded zone, with specific zones of tensile stresses misplaced at the weld center, with values up to 391 MPa, and compressive stresses, with values up to -166 MPa, as it moves away rails weld center. An important point of this study is the residual stress measurement considering a complete welding process, including: pre-grinding, flash butt welding, heat treatment, finishing grinding and straightening. Lastly, was observed the welding technique potentially can induce residual stresses at rails.

No abstract

Arc welding processes are widely used in the industrial sector, mainly for productivity and continuity. However, these processes have several undesirable results, such as distortions and residual stresses (RS). When compared to other welding processes, the RS level can make the welded joint unfeasible. Many studies on these arc welding discontinuities have been carried out in experimental and numerical areas about their measurement, analysis, and control, however, not yet clearly enlightened, since it is a complex topic, both for industry and academia, needing to be deepened. This study aims to present a contextualized approach to destructive and non-destructive techniques used to measure RS generated by arc welding, as well as the influence of these distortions and stresses on the welded structures and, finally, to present possible control techniques. Finally, this study highlights the use of CW-GMAW welding, which achieved a reduction in stress and distortion levels, due to the introduction of a non-energized wire in the arc of the GMAW process, as evidenced by the results of RS measured by X-ray diffraction (XRD) and acoustic birefringence (AB). Thus, in this context, the approach to RS in arc welding presented here is extremely relevant for researchers involved with the topic.

The GMAW (Gas Metal Arc Welding) process is an electric arc welding technique widely used around the world due to its ease of use, low equipment cost and, mainly, due to the high deposition rate, the quality of the metal of solder, which makes it versatile and susceptible to modification. Thus, variants such as CW-GMAW (Cold Wire–Gas Metal Arc Welding), DCW-GMAW (Double Cold Wire–Gas Metal Arc Welding), and HW-GMAW (Hot Wire–Gas Metal Arc Welding) emerged from the conception of small adaptations to the original process that ended up generating better and more adjusted results than GMAW. Thus, variations of some parameters will be shown and their respective effects on the weld bead geometry, dilution, penetration, deposition rate, in addition to the effects on macro and microstructure. This provides the possibility of using the variants in different types of applications in the industry in general. Where the application in narrow 4 mm chamfer has already been observed, reduction of residual stresses, increase in fatigue resistance and coatings with special alloys.