Bubble Gum: A poor quality weld that looks like chewed bubble gum. Busted Out: Failed a weld test.
There are three types: check cracks, root cracks, and full centerline cracks. Check cracks are visible from the surface and extend partially into the weld. They are usually caused by high shrinkage stresses, especially on final passes, or by a hot cracking mechanism.
Too much or too little penetration: If the weld penetrates too little, the joint will be weak, and if it over-penetrates, the backside of the joint could have a poor finish. Undercutting: If the parent metal thins at the edges of the weld, it typically indicates filler metal relative to the current.
Internal Welding Defects
Common examples include slag inclusions, incomplete penetration, incomplete fusion, etc.
Weld defects are often caused by improper technique or parameters, such as poor shielding gas coverage or incorrect travel speeds.
Common causes of weld undercut include excessive voltage with too fast of travel speeds and improper gun angle. When the voltage is too high, the arc tends to push the molten weld pool out of the joint. To prevent the problem, lower your voltage and reduce your travel speeds.
Too Much Heat May Break a Weld
If you're welding with too much power and melting a lot of the metal, you'll cause the metal to expand and contract too much during the welding process. This will create an unstable weld joint and will lead to a weaker weld by the time you're done.
Cracks. These are the most serious of weld defects because they can easily cause the failure of the welded structure. Depending on the orientation of the crack in the weld, it can be classified as longitudinal or transverse.
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).
Distortion occurs during the expansion and contraction of the weld and base metals during the heating and cooling cycle. It means that the welded component fails to maintain its original shape and may result in shrinkage, angular movement, or buckling.
Among the commonly known welding defects, incomplete penetration and fusion, porosity and slag inclusions are the most common to affect welding strength.
Spatter – Spatter occurs when metal particles from the weld is stuck on the area adjacent to the weld area. This defect is common in gas metal arc welding and it is sometimes very hard to remove the particles.
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.
Visual Inspection Of The Weld
The basic method of checking the quality of a weld is to inspect it for any flaws visually. Look for any cracks, beads, bends, craters, excessive reinforcements, or other flaws and inform any concerned authorities about it.
Excessive spatter
This defect results when the weld puddle expels molten metal and scatters it along the weld bead. The result? Molten metal fuses to the base, causing bumps or spatter. Typically spatter needs to be removed mechanically, by scraping or grinding it off with a grinder.
Too fast of a wire feed speed, too high of a voltage setting, and too long of a welding wire extension, or stick-out, can cause spatter. Lowering the given settings and using a shorter stick-out can help. Like porosity, insufficient shielding gas and/or dirty base materials can cause spatter.
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.
Stick or Arc welding
Stick welding is a manual arc welding process that uses a consumable electrode covered with a flux to lay the weld. It produces strong welds and works well with thicker materials. It is a versatile welding process, is simple to set up the equipment, and is generally easy to learn.
The four main types of welding are: Gas Metal Arc Welding (GMAW/MIG), Gas Tungsten Arc Welding (GTAW/TIG), Shielded Metal Arc Welding (SMAW), and Flux Cored Arc Welding (FCAW).
TIG is the hardest form of welding for various reasons such as being a tedious process, and it is harder to master than other forms of welding. Now, I will show you why TIG is the hardest form of welding.