Influence of the speed of air currents on the porosity in joints soldered by theMIG/MAG process

ABSTRACT

A typical recurring defect in welded joints, due to climatic conditions such as wind and humidity, is the presence of porosities in the weld bead. And, depending on the severity of this factor, it may cause it to fail due to mechanical stresses. Therefore, the present work aimed to quantitatively analyze the influence of differ- ent airflow velocities on the level of porosities in joints welded by the MIG / MAG process. For this purpose, a survey of the average wind speeds in the northeastern region was carried out and with these data in hand, such conditions were imposed in the laboratory during welding. Finally, the weld beads were analyzed using optical microscopy and the pore quantification for each of the imposed conditions. It was concluded that an airflow velocity of 2.3 m / s provided a porosity level of 3.41 pores / cm², with average dimensions of 3.96 mm, an average straight line between the pores 7.97 mm and an average cord height of 9.0 mm. The samples sub- mitted to the airflow velocity of 3.6 m / s presented an average pore value of 2.31 pores / cm² per sample, an average pore diameter equal to 3.57 mm, an average distance in straight line between the pores of 6.40 mm and an average color height of 9.77 mm. When the samples are welded at 2.3 and 3.6 m / s, in non-compliance with the AWS A5.20A5.20M-2005 standard.

Keywords
Field welding; Air flow; GMAW process