A welding defect is any irregularity in the weld arising from a poor welding procedure. They can occur externally, internally, or even specifically in the process. Sometimes, these imperfections may result due to a change in the properties of the work piece material.
The ASME or American Society of Mechanical Engineers has divided the cause for these defects as given:
41% due to poor welding procedures
32% due to the errors caused by the operators
12% due to a wrong welding technique
10% is of wrong flux or welding consumables
5% to a poorly grooved work-piece.
A weld defect is a problem that happens during welding and makes the joint weaker than it should be. These problems can make the weld less effective or less attractive. Weld defects can happen because of incorrect welding techniques or patterns. They can change how the weld looks, how big it is, and how strong it is. Defects can appear inside or on the surface of the weld. Some minor defects might be okay if they meet the allowed standards, but serious issues like cracks are never acceptable. Simply put, a weld defect is any mistake that reduces the quality of the weld.
Types of Welding Defects
Welding defects can be of different types based on various reasons for the irregularity. There are three types: External, Internal, and Process specific.
External Welding Defects
External welding defects are problems with the weld that can be seen with the naked eye under normal conditions. These defects are easy to spot and can be fixed using different methods.
Cracks
The worst welding defect that is considered to be unacceptable without a second thought is the crack in the weld. These defects can progress rapidly affecting the whole weld and causing failure.
Longitudinal Cracks: They are formed parallel to the weld bead.
Transverse Cracks: They are formed along the width of the weld bead.
Crater Cracks: They are formed at the end of the bed.
Hot Cracks: These happen when the base metal is heated to extremely high temperatures above 10,000°C. As the weld joints cool and solidify, cracks can form. This often occurs if the wrong type of filler metal is used or if the metal cools down too quickly.
Cold Cracks: These can take hours to days to be visible, usually after the cooling of metal.
