The electrode weakness , one kind of defect is the porosity in the weld, which is caused by the humidity and pollution around the weld. It may come from the electrode coating, the material surface or the surrounding atmosphere. The porosity may also be caused by the welder using too long arc, which is especially prominent for the low hydrogen electrode. Therefore, the short arc will help to reduce the porosity.
Blowholes may also be caused by the so-called "arc partial blow" phenomenon, which exists in all the arc welding, which is a common problem and often makes the manual welding welder very distressed
(1) to understand the partial arc blowing, first of all, it is necessary to know that when the current passes through the conductor, a magnetic field will be generated around it, and the direction of the magnetic field is perpendicular to the direction of the current, which can be regarded as a group of concentric circles around the conductor.
(2) reduce welding current
(3) tilt the electrode in the opposite direction of arc blowing
(4) use large tack welding at both ends of the joint and intermittent tack welding in the joint
(5) welding in the direction of large tack welding or finished welding
(6) step back welding method
(7) keep away from the grounding to reduce the back blowing of the arc, and toward the grounding to reduce the front blowing of the arc
(8) connect the cable to both ends of the weld
(9) wind the cable around the workpiece, and the current direction shall be able to produce a magnetic field to offset the arc bias blow
(10) add arc extinguishing plate at the end of joint
In addition to air holes, partial arc blowing will also lead to spatter, undercut, poor forming and reduce welding penetration.
As long as the protection is provided by flux, slag inclusion may occur, and manual arc welding is no exception. The welder can reduce the possibility of slag inclusion by fully floating the slag to the surface of the molten pool. In addition, in multi pass welding, before the next layer of welding, the slag on the weld bead can be completely cleaned to reduce the occurrence of slag inclusion.
Because manual arc welding is completed by manual operation, if it is not used properly, there may be various defects, such as incomplete fusion, incomplete penetration, crack, undercut, weld beading, incorrect weld size and improper weld cross section.