16 Common Types of Welding Defects [Causes, Remedies] PDF (2024)

FAQs

What is welding defects types causes and remedies? ›

Welding defects can occur at any stage of the welding process and they can affect both the inside and outside of the metal structure. Although it is almost impossible to create a defect-free weld, it is important for you to reduce their occurrence to prevent loss of material and maintain the intended quality.

Welding is a permanent joining process in which two pieces of metal join together to form one piece by heating the metals to their melting points. Additional metal, also called filler metal, is added during the heating process to help bond the two pieces together.

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.

Porosity is caused by the absorption of nitrogen, oxygen and hydrogen in the molten weld pool which is then released on solidification to become trapped in the weld metal. Nitrogen and oxygen absorption in the weld pool usually originates from poor gas shielding.

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.

Among the commonly known welding defects, incomplete penetration and fusion, porosity and slag inclusions are the most common to affect welding strength.

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).

When it comes to imperfections for steel welds, there are two types: discontinuities and defects. A discontinuity is an imperfection in the physical structure of a material, which changes its properties. A discontinuity can be classified as internal, external, volumetric, and planar.

What is a cold weld defect? ›

Cold lap is a type of weld defect which occurs when molten metal does not completely fuse with the cold plate surface. This produces a crack like defect, often very small, which is parallel to the plate. The cold lap weld defect has been classified into three types namely spatter, overlap and spatter-overlap cold lap.

Cause. Porosity is caused by the absorption of nitrogen, oxygen and hydrogen in the molten weld pool which is then released on solidification to become trapped in the weld metal. Nitrogen and oxygen absorption in the weld pool usually originates from poor gas shielding.

Shielded Metal Arc Welding (Stick) is the most popular welding process. It is the most versatile and uses the simplest equipment.

These include metal inert gas (MIG) welding, stick welding, tungsten inert gas (TIG) welding also know as gas tungsten arc welding (GTAW), gas welding, metal active gas (MAG) welding, flux cored arc welding (FCAW), gas metal arc welding (GMAW), submerged arc welding (SAW), shielded metal arc welding (SMAW) and plasma ...

A crack may be defined as a local discontinuity produced by a fracture which can arise from the stresses generated on cooling or acting on the structure. It is the most serious type of imperfection found in a weld and should be removed.

Hot cracking occurs when the available supply of liquid weld metal is insufficient to fill the spaces between solidifying weld metal, which are opened by shrinkage strains. Thus, hot cracking occurs when: Strain on the weld pool is too high.

Undercut can occur for several reasons: Excessive heat from high current and voltage settings. If the travel speed is too fast, the electrode moves away from the weld pool prematurely. If edges are not prepared properly dirt or grit on the welding surfaces tends to block heat transfer which can cause undercutting.

Weld cracking refers to a depression left at the termination of a weld where the weld pool is left unfilled. Most forms of weld cracking result from the shrinkage strains that occur as the weld metal cools. If the contraction is restricted, the strains will induce residual stresses that cause cracking.

What is slag from welding? ›

The American Welding Society (AWS) defines slag as “a nonmetallic byproduct of the mutualdissolution of flux with nonmetallic impurities in welding and brazing processes.” In short, it is the hardened layer left on the top of weld made during flux-cored welding (FCAW).

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.

Internal cracking forms cracks inside the weld. Typical cracking types classified as internal defects are weld metal cracking (root cracking) and heat-affected-zone (HAZ) cracking (underbead cracking). Weld metal cracking is a defect produced inside the molten metal.

Surface Cracks, Undercut, Porosity, Overlaps, Crater, Underfill, Spatters, Excessive penetration, Arc Strike, etc are examples of external welding defects. Internal welding defects exist in the material at some depth and are hidden from naked eyes.

TIG welding is susceptible to the same type of weld defects you find in MIG welding, such as lack of fusion, burn through, crater/crater cracks, undercut and porosity in the weld metal. All these defects can occur due to improper welding techniques.

Acetylene is the only fuel gas suitable for gas welding because of its favourable flame characteristics of both high temperature and high propagation rates. Other fuel gases, such as propane, propylene or natural gas, produce insufficient heat input for welding but are used for cutting, torch brazing and soldering.

Fabrication welders, also known as Welding Fabricators, do just this. Fabrication welders use engineering drawings to cut metal into designated shapes and weld them together to form a specific structure.

Three of the most common are Arc, MIG (Metal, Inert Gas) or GMAW (Gas, Metal Arc Welding), and TIG (Tungsten Inert Gas) welding. In order to know which process is best for the particular job you're working on, here's what you should know about each of them. Arc welding is the oldest of these three welding processes.

Root gap - the minimum distance between the ends of the elements to be welded which is measured during the assembly of the butt joint for welding. positioning and measurement taking. Lower the fillet arm 2 or the taper gauge 5 into the groove until they come into contact with the ends of the elements to be welded .

What are the causes of incomplete fusion? ›

Common causes of incomplete fusion include incorrect angle and/or positioning of the welding gun, incorrect weaving technique when filling a joint, travel speed too slow or too fast, inaccurate settings such as amperage too low, or contamination and/or insufficient cleaning of the base metal.

DIMENSIONAL Welding-defects can be assessed by visual inspection and by measuring with simple weld gauges. They derive from improper set up or by distortion which should be controlled in a proper fixture, or by a different welding sequence. In general they should be corrected by employing proper means before welding.

UNDERFILL. Definition. The amount of weld that is below a straight line drawn from the edges of the joint preparation of a groove weld, with the exception of allowable undercut.

What is Lift-Arc TIG Ignition ? With Lift-Arc Ignition feature, to start the arc the tungsten electode is touched on the job and lifted off. The start-up current is very low and therefore the tungsten barely sticks to the job and the sharpened point is not damaged. The tungsten is then easily lifted off the job.

Porosity in welding happens when a contaminant or gas is absorbed into the weld puddle. These impure welds are commonly referred to as cavities.

2 refers to a horizontal position – either 2F or 2G. 3 is a vertical position – either 3F or 3G. 4 is an overhead position – either 4F or 4G.

​An electrode's travel angle is measured in a plane defined by the weld axis and the electrode axis. The travel angle is the angle measured between the axis of the electrode and the axis of an imaginary line perpendicular to the weld axis.

Welding distortion can be defined as “the non-uniform expansion and contraction of weld metal and adjacent base metal during the heating and cooling cycle of the welding process”. Distortion is a consideration when arc welding all materials, and the principals behind this reaction are fundamentally the same.

Welding defects can be defined as weld surface irregularities, discontinuities, imperfections, or inconsistencies that occur in welded parts.

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.

How many types of welding are there? ›

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).

Porosity is caused by the absorption of nitrogen, oxygen and hydrogen in the molten weld pool which is then released on solidification to become trapped in the weld metal. Nitrogen and oxygen absorption in the weld pool usually originates from poor gas shielding.

Cold lap is a type of weld defect which occurs when molten metal does not completely fuse with the cold plate surface. This produces a crack like defect, often very small, which is parallel to the plate. The cold lap weld defect has been classified into three types namely spatter, overlap and spatter-overlap cold lap.

Weld defects are often caused by improper technique or parameters, such as poor shielding gas coverage or incorrect travel speeds.

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.

Acetylene is the only fuel gas suitable for gas welding because of its favourable flame characteristics of both high temperature and high propagation rates. Other fuel gases, such as propane, propylene or natural gas, produce insufficient heat input for welding but are used for cutting, torch brazing and soldering.

Shielded Metal Arc Welding (Stick) is the most popular welding process. It is the most versatile and uses the simplest equipment.

Cause. Porosity is caused by the absorption of nitrogen, oxygen and hydrogen in the molten weld pool which is then released on solidification to become trapped in the weld metal. Nitrogen and oxygen absorption in the weld pool usually originates from poor gas shielding.

What causes wormhole porosity? Wormhole porosity is a defect where there are indentations on the surface of the weld. This usually happens with FCAW when there is nitrogen trying to escape the weld as it is solidifying. The result is an elongated divot in the weld, often accompanied by pinholes.

What causes weld spatter? ›

Weld spatter is formed from droplets of molten metal or non-metallic material that can be produced during a welding process. The drops of hot material can spray or splash from the weld and hit the workbench, floor, base material or other surrounding area.