A weld defect results from a poor weld, weakening the joint. It is defined as the point beyond the acceptable tolerance in the welding process. Imperfections may arise dimensionally, wherein the result is not up to standard. They may also take place in the form of discontinuity or in material properties.
Weld defects are often caused by improper technique or parameters, such as poor shielding gas coverage or incorrect travel speeds.
Signs of a bad weld include: Underside of weld has insufficient penetration, excessive globules of metal, over-sized weld, undersized welds, undercut, overlap, incomplete fusion, porosity and/or cracking. Excessive grain growth or the presence of hard spots cannot be determined visually.
The most stringent cosmetic stipulation is for the appearance of a surface (usually customer-visible) to be free from markings or imperfections such that a weld is not visible after painting. Other requirements may limit the displacement, indentation, or distortion of the parent metal.
These impure welds are commonly referred to as cavities. Basically porosity in welding is a weak, bubble-filled weld that does not meet code and more importantly can in some cases, cause part of a project to become weak and collapse. If you find that your weld has this impurity it must be redone immediately.
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.
Both acute and chronic health risks are associated with welding fume. Occupational lung disease, including lung cancer, is the most common health risk, but welding can also affect the eyes and skin.
Although sparks from welding can be harmful to a welder's eyes, particles from pre- and post-weld grinding, brushing, and chipping pose an even greater risk. Direct and indirect exposure to UV and IR rays can both cause eye damage. In a shop with two other welders late at night, I got the worst eye burns of my life.
Most of the time, burn-through occurs due to excessive heat input into the weld joint Heat input is mainly dependent on amperage (or current). So, the higher the current, the greater the heat input. If you see burn-through in your weld, double-checking your amperage level should be the first thing you do.
A: Excessive weld spatter can result from voltage that's too low or from welding on material that is dirty or has mill scale. Be sure to clean the base material and remove mill scale (or avoid it altogether when possible) and make certain that shielding gas flow is adequate.
The milk theory is based on the belief that when welders drink milk, the calcium in the milk will “saturate the body” and prevent the body from absorbing toxic heavy metals that can be found in welding fumes, such as cadmium.
That's why it's sometimes called 'welder's flash' or 'arc eye'. Flash burns are like sunburn in the eye and can affect both your eyes. Your cornea can repair itself in one to two days, and usually heals without leaving a scar. However, if the flash burn is not treated, an infection may start.
Exposure to infrared light can heat the lens of the eye and produce cataracts over the long term. Visible light from welding processes is very bright and can overwhelm the ability of the iris of the eye to close sufficiently and rapidly enough to limit the brightness of the light reaching the retina.
Pneumosiderosis, or more commonly referred to as Welder's lung, is an occupational lung disease that occurs after chronic inhalation of iron dust particles, especially in welders.
Welding fumes are far worse for you than smoking. Any time you weld you should be wearing a respirator with appropriate filters to the situation or even an approved fresh air supplied mask with an approved supply of fresh air(NOT off your shop compressor, it contains oil).
Cons of the Welding Profession
Welders may experience some dangers and discomfort on the job including burns, eye discomfort, exposure to hazardous materials and a lot of physical effort. You may find yourself in tight spaces, working in hot weather or welding in wet and cold environments.
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.
The bond, however, is only as strong as the joining material. Welding, on the other hand, cuts out the middleman and joins the original pieces directly to each other. The result is a strong, cohesive bond that's often as strong as the material itself.
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.
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.
To put it in a nutshell: Cooling a welding torch with water destroys the torch – but also as a consequence the power source and other components of the torch system involved. Therefore: Water as a coolant is definitely not recommended!
Weld spatters are a welders biggest enemy and have a massive negative influence on the productivity as they may force major downtimes. But there are ways to reduce weld spatters and therefore significantly decrease cleanup time as well as increase productivity.