What are the 12 most common discontinuities in welding?

Weld discontinuities can be defined as "an interruption of the typical structure of a weld, such as a lack of homogeneity in the mechanical, metallurgical or physical characteristics of the weld." Weld discontinuities include porosity, slag inclusions, incomplete fusion, incomplete joint penetration, excessive melt- ...

What are the 12 common discontinuities?

What Are Some Common Welding Discontinuities?

• Porosity. Porosity occurs when gas becomes trapped in the weld pool, forming permanent bubbles as the metal cools from a liquid state back to a solid. ...
• Inclusions. ...
• Inadequate Joint Penetration. ...
• Incomplete Fusion. ...
• Arc Strikes. ...
• Overlap.

What is the 10 welding defects?

Among the discontinuities related to the welding process, one can mention 10 types: Lack Of Penetration or Incomplete Penetration. Lack Of Fusion or Incomplete Fusion. Undercut.

What are the common defects in welding?

Most defects encountered in welding are due to an improper welding procedure. Once the causes are determined, the operator can easily correct the problem. Defects usually encountered include incomplete penetration, incomplete fusion, undercutting, porosity, and longitudinal cracking.

What is the most common weld defect?

Cracks – Cracks are the most common defects and they can occur anywhere on the surface of the weld material. Some cracks can also be present inside the weld material especially on areas that are affected by direct heat (HAZ).

WELDING DEFECTS!! Porosity, Arc Strikes, Undercut

What are 5 welding defects?

Following are the types of welding defects:

• Porosity and Blowholes.
• Undercut.
• Weld crack.
• Incomplete fusion.
• Slag inclusion.
• Incomplete penetration.
• Spatter.
• Distortion.

What is a weld discontinuity?

Weld discontinuities can be defined as "an interruption of the typical structure of a weld, such as a lack of homogeneity in the mechanical, metallurgical or physical characteristics of the weld." Weld discontinuities include porosity, slag inclusions, incomplete fusion, incomplete joint penetration, excessive melt- ...

What are different types of defects?

Common Types of Defects

• Arithmetic Defects.
• Logical Defects.
• Syntax Defects.
• Multithreading Defects.
• Interface Defects.
• Performance Defects.

What are the various types of welding defects explain any seven types?

We can break down weld defects into the following main categories;

• Inclusions.
• Lack of fusion.
• Porosity.
• Undercut.
• Under-fill.
• Cracks.
• Excess reinforcement and excess penetration.
• Over-roll/Overlap.

What are the two types of welding defects?

Welding defects are broadly classified into two categories, and those are: External welding defects (Defects occur on the upper surface of the welded work). Internal welding defects (Defects occur under the surface of the welded work).

What causes porosity?

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 is the difference between a weld defect and discontinuity?

A Discontinuity is an objective lack of material, an interruption in the physical consistence of a part while a Defect is an excessive conditions, outside the acceptance limits, which risks to compromise the stability or the functionality of the welded structure. It is very hard to perfect welding.

What are the common welding troubles and explain its causes and remedies?

Undercut

• Too high weld current.
• Too fast weld speed.
• The use of an incorrect angle, which will direct more heat to free edges.
• The electrode is too large.
• Incorrect usage of gas shielding.
• Incorrect filler metal.
• Poor weld technique.

What is a Nick break test in welding?

The Fracture or Nick Break Test is used to determine the quality of a weld, and involves breaking open the weld length-wise, and then visually inspecting the exposed weld interior for any internal imperfections such as lack of sidewall fusion, lack of inter-run fusion and porosity.

Which of the following is the welding defect *?

Welding spatter is a welding defect. During welding operation due to the force of arc, some of the molten metal particles are jumping from the weld pool, and falling into other areas of the plate is called spatter.

How are point defects classified 12?

There are 3 types of point defects: Stoichiometric defect. Frenkel defect. Schottky defect.

What is a defect list?

A defect list is exactly what the name suggests, it is a list of items, made by the client or the builder and client alike, that determine what is required to be finished.

What are major defects?

A 'major defect' is defined in the Act to mean a defect in a 'major element' of the building. That defect must be likely to cause an inability to use the building for its intended purpose, or destruction or threat of collapse of all or part of the building.

What weld discontinuity is considered to be the most severe?

Cracks – Cracks are the most detrimental discontinuity for the integrity of a welded connection. Cracks, in any amount, will constitute a defect with very few exceptions.

Is porosity a discontinuity?

Porosity is defined as cavity-type discontinuities formed by gas entrapment during solidification. Porosity is caused by gases that are present in the molten weld.

What is a discontinuity in NDT?

Discontinuity: a lack of continuity or cohesion; an intentional or unintentional interruption in the physical structure or configuration of a material or component. Flaw: an imperfection or discontinuity that may be detectable by nondestructive testing and is not necessarily rejectable.

What is a cold weld defect?

LACK OF FUSION Lack of fusion, also called cold lapping or cold shuts, occurs when there is no fusion between the weld metal and the surfaces of the base plate. This defect can be seen in Figure 10-2. The most common cause of lack of fusion is a poor welding technique.

What is undercut in a weld?

In welding, undercutting is when the weld reduces the cross-sectional thickness of the base metal. This type of defect reduces the strength of the weld and workpieces.

How many types of welding are there?

There are four main types of welding. MIG – Gas Metal Arc Welding (GMAW), TIG – Gas Tungsten Arc Welding (GTAW), Stick – Shielded Metal Arc Welding (SMAW) and Flux-cored – Flux-cored Arc Welding (FCAW). We dive deeper into each type of welding here.

Which of the weld defects occur due to incorrect welding techniques?

Which of the following defects occur due to incorrect welding techniques? Explanation: Cracking in weld metal defect occur due to incorrect welding techniques.