Wrong technique. “Push vs. pull, gun/electrode angle, travel speed, and arc length can all lead to problems,” Leisner says. For example, if the rate of travel is too slow, the pool of weld metal will deposit an excess of weld metal.
Where cracking occurs in or adjacent to welded joints, a satisfactory repair may be made by welding. It is important that the cracked material is gouged or machined away sufficiently to permit a full penetration repair weld to be made, with no traces of crack left behind and no new significant defects introduced.
Signs of a bad weld include: Lack of uniformity, cracks down the middle of the bead, too thin, and/or a lack of discoloration of the parent metal (which should be about 1/8 of an inch).
Bubble Gum: A poor quality weld that looks like chewed bubble gum. Busted Out: Failed a weld test.
The major cause of a crack is when internal stresses exceed the strength of the weld metal, the base metal, or both. And once a focal point for these stresses—that is, a stress riser—develops and accumulates, a crack can propagate.
A weld that is too small or too short for the application can fail from tension, compression, bending or torsional loads. If a weld is made to be in an application where a cyclical load is going to be applied, it will be beneficial to consider a filler metal option with increased impact toughness and ductility.
TIG welding is the hardest form of welding to learn for a variety of reasons. The process of TIG welding is slow and takes time to get used to as a beginner. A TIG welder requires a foot pedal to feed the electrode and control the variable amperage while maintaining a steady hand at the welding torch.
It should be remembered that welding over weld metal is actually a very common occurrence. Multi-pass welds after all are manufactured by welding over weld metal! There are also many accepted procedures in which welds overlap.
Be sure the welder is properly installed and grounded. Never weld without adequate ventilation. Take proper precautions to prevent fires. Protect your entire body with fire retardant clothing, shoes, and gloves.
Among the commonly known welding defects, incomplete penetration and fusion, porosity and slag inclusions are the most common to affect welding strength.
Health hazards from welding, cutting, and brazing operations include exposures to metal fumes and to ultraviolet (UV) radiation. Safety hazards from these operations include burns, eye damage, electrical shock, cuts, and crushed toes and fingers.
This means that once the weld pool has developed the wire is then dipping into a liquid. If this then becomes too runny, the dipping of the wire creates a popping effect much like a needle popping a balloon, and this can pop it causing a hole.
Pinholes are small holes in a weld puddle that appear after welding. They can be as deep as the weld and ruin an otherwise perfect weld. The main reason for pinholes is the presence of impurities in the weld puddle caused by the gases released by the welding gun.
An edge joint is the weakest type of weld join, so isn't suitable for load-bearing jobs.
The sign of a quality and secure weld is that you will not see the weld at all. If there is any visible evidence of a weld, it will be in the form of a bead that has no holes or cracks and is uniform overall. A high-quality weld is made using high-quality materials.
Too much heat will likely cause cracking in the weld, oxide inclusion, softening of the heat-affected zone, and porosity—all of which degrade your material and affect the quality of your weld, both structurally and cosmetically.
Too cold and the bead is sitting on top of the work piece with little or no penetration. Too hot and it is probably burning through. As you move towards the middle, you may need to examine the weld bead closer. If the current is too low and wire speed too high, the resulting weld bead is taller with steeper edges.