The most important challenge in narrow gap gas metal arc welding (NG-GMAW) is to maintain uniform and sufficient penetration at both the groove faces, this aspect is commonly referred to as sidewall fusion. Associated causes of a lack of sidewall fusion are: torch design, tracking system, low heat input, electrode diameter, electrode cast, width of groove, welding parameters, power supply characteristics and magnetic arc blow. Adequate literature is available on all these aspects except on effect of the magnetic field which is the cause of arc blow. In the present investigation, the effect of the magnetic field on the lack of sidewall fusion was studied. The effect of the change in the welding direction with different wire diameters (1.2 mm and 1.6 mm) and torch oscillation on the residual magnetism and subsequently on the extent of the sidewall fusion was checked by the side bend test. It was assumed that the direction of the movement of the torch induces the magnetic field and the magnetism induced in the job will have an opposite direction when the direction of the travel of the torch is reversed. The residual magnetism is also responsible for the lack of sidewall fusion and can be controlled by reversing the welding direction after each two runs and after each run. 1.2 mm electrode wire is preferable over 1.6 mm electrode for controlling the residual magnetism.
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