Is it necessary to leave a gap for the welding wire to melt in when welding a 0.25 mm thick steel strip?

Yes When welding a steel strip with a thickness of 0.25mm, a gap should be left so that the welding wire can be melted in. The weld bead with a little gap is easy to see. The purpose of leaving a gap in the weld is to ensure the penetration of the weld root. Covered electrode arc welding is a welding process which uses the arc generated between covered electrode and weldment as the heat source to realize welding.