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Welding Defects & its Prevention
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Sk Nahidul ISLAM Shrabon
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Welding Defects & its Prevention 
 
 
 
 
 
 
Prepared by 
SK. Nahidul Islam Shrabon 
March 30, 2024 
 
Table of contents 
 
 Abstract. 
 What are weld discontinuities? 
 What are welding defects? 
 How welding defects occur? 
 Some common types of welding defects. 
 How to find welding defects? 
 Prevention of welding defects. 
 Conclusion. 
 References. 
 
 
 
 
 
 
 
 
Abstract 
Welding defects are a significant issue in various industries, affecting the 
quality of structures and components. Causes include material-related 
issues, process-related factors, design flaws, and human errors. Common 
defects include porosity, lack of penetration, undercutting, incomplete 
penetration, weld cracking, and distortion. Detecting defects is crucial for 
structural integrity and performance. Non-destructive testing techniques 
like ultrasonic, radiographic, and magnetic particle testing are used. 
Preventing defects requires a comprehensive approach including material 
selection, proper welding procedures, joint preparation, shielding, 
equipment maintenance, and skilled workforce training. 
 
A Welding Discontinuity 
Weld discontinuities are irregularities or imperfections in the welding 
process, resulting in deviations from the ideal joint, which can 
compromise the weld's integrity and strength, potentially leading to 
defects or failures. This could be manifested in terms of: 
 Varied porosity 
 Incomplete fusion or joint penetration 
 Unacceptable profiles 
 Subtle tears and cracks 
 
Welding Defects 
Welding defects are imperfections or discontinuities in a weld that 
compromise the strength, integrity, or appearance of the joint. They can 
be caused by a variety of factors, including: 
 Incorrect welding procedures or techniques 
 Improper cleaning or preparation of the weld joint 
 The use of incorrect welding consumables 
 Welding at incorrect travel speeds or amperages 
How to distinguish between weld discontinuity 
and weld defects 
Weld discontinuities are interruptions in the normal flow of a weldment’s 
structure. This may either be in the parent metal or the weld metal, and 
they occur due to wrong welding methods or patterns. These irregularities 
often differ from desired weld bead sizes, shapes, and intended quality. 
They can also be internal or external. 
 
The following points distinguish welding defects from discontinuities: 
 A weld would become a defect if the quality control department 
completely rejected the product. 
 A discontinuity can survive field tests, but a defect cannot. 
 Discontinuities often have a defined list of acceptable limits before 
rejection. 
 Weld discontinuities are usually within acceptable manufacturing 
error margins, but defects must be repaired or rejected. 
 
That said, if discontinuities exceed stated project limits, they may become 
a weld defect. Ultimately, it is vital to inspect welding processes using 
efficient methods. 
Welding defects occurrences 
Welding defects can be caused by various factors including improper 
welding techniques, incorrect parameters, poor welder skill or training, 
material issues, inadequate preparation of base metal, environmental 
factors, malfunctioning or improperly maintained welding equipment, 
residual stress and distortion, and inadequate inspection and quality 
control. Inadequate welding techniques can lead to incomplete fusion, 
excessive heat input, and distortion. Incorrect parameters can result in 
insufficient penetration, incomplete fusion, or excessive spatter. 
Insufficient training or experience of welders can also contribute to 
welding defects. Material issues, such as impurities, contamination, or 
improper composition, can also affect weld quality. Environmental 
factors like humidity, temperature, and wind can also affect the welding 
process. Insufficient inspection and quality control measures can lead to 
undetected defects. Addressing these issues is crucial for producing high-
quality welds and reliable welded structures. 
 
Types of Welding Defects 
Welding faults and defects can be categorized according to their location 
in the metal. They may be external or internal. 
 
External Welding Defects 
These are superficial or visual defects. They manifest on the surface of 
the metal weldment. External weld defects are usually detectable via 
visual inspection or other methods like Magnetic Particle Inspection 
(MPI) or Dye Liquid Penetrants (DPI). Typical examples are cracks, 
undercuts, overlaps, porosity, spatter, etc. 
 
Internal Welding Defects 
Internal defects occur within the metal material and are usually not open 
to the weld’s surface. It is often difficult to detect these defects with visual 
inspection and some non-destructive tests. However, they are detectable 
using methods like Ultrasonic Testing and Radiographic Testing (RT). 
Common examples include slag inclusions, incomplete penetration, 
incomplete fusion, etc. 
 
 
Different types of welding defects and their remedies 
 
1. Weld Crack 
 
Source from: welding.org.au 
Cracks are perhaps the most unwanted welding defects. They are 
imperfections produced due to the local rupture from the effects of 
stresses and cooling. They are often significant because their geometry 
creates a large stress concentration at the tip of the crack. Therefore, the 
weldment is prone to fracture. Welding cracks can come in various sizes, 
shapes, and types, including: 
 
 Longitudinal 
 Transverse 
 Crater 
 Radiating 
 Branching 
 
 
Depending on the temperature they occur,cracks can be: 
 
Hot Cracks 
These occur during the solidification and crystallization of weld joints. At 
this stage, the temperature is often over 10,000 degrees Celsius. They can 
either be solidification cracks or liquation cracks. The former occurs when 
the metal contains high impurity or carbon content or when there is a 
disruption in heat flow. On the other hand, liquefication cracks occur due 
to increased heating temperature. This causes the liquefaction of 
constituents with low melting points. 
 
Cold Cracks 
These are “delayed” cracking defects that develop after the solidification 
of weld metal. They can occur many days after welding is completed. 
These types of cracks often lie parallel to the fusion boundary. Residual 
tensile stress may also cause the cracks to grow away from the fusion 
boundary. Cold cracks occur mainly due to a lack of preheating, high 
stresses, low temperature, high hydrogen content, susceptible material 
structure, etc. 
 
Causes Of Weld Crack 
 Poor ductility or contamination of given base metals. 
 Combining high welding speed with low current. 
 High residual stress solidification from shrinkage. 
 Lack of preheating before starting welding. 
 The high content of sulfur and carbon in base metals. 
 Using hydrogen as shielding gas for welding ferrous metals. 
 
Remedies for Weld Crack 
 Use suitable metal materials and clean their surfaces before welding. 
 Use the right welding speed and current. 
 Preheat the base metal and reduce the cooling speed joint. 
 Use the appropriate sulfur and carbon mixture. 
 Reduce the gap between weld joints. 
 
2. Crater 
Craters are special kinds of cracks that occur after the welding process 
before the completion of weld joints. It often occurs due to improper 
filling of the crater before breaking the arc. This leads to faster cooling of 
the outer edges than the crater. Insufficient volume of the weld may 
prevent it from overcoming metal shrinkage. As a result, a crater crack 
defect in the welding process is formed. 
 
Causes of Crater 
 Improper filling of the crater. 
 Incorrect torch angle. 
 Wrong choice of welding technique. 
 
Remedies for Crater 
 Ensure proper filling of the crater. 
 Use a suitable torch angle for lowering stress on the metal. The torch 
angle for wire welding should be between 10 to 15 degrees in the 
direction of the weld. On the other hand, you should maintain an 
angle of 20 to 30 degrees (in the dragging direction) for stick 
welding. With a fillet weld, hold the wire or rod at 45 degrees 
between the metal pieces. 
 Use a small electrode. 
 Choose the correct welding technique. 
3. Undercut 
 
 
Source from: welding.org.au 
 
Undercut defects are irregular grooves formed in the shape of notches on 
the base metal. They occur due to the melting of the base of metal away 
from the weld zone and are characterized based on their length, depth, and 
sharpness. Undercut defects in welding run parallel to the weldment, 
causing a loss in thickness. As a result, the weld joint becomes more 
susceptible to fatigue. The types of undercuts are: 
 Continuous undercut 
 Inter-run undercut 
 Intermediate undercut 
 
Causes of Undercut 
 Using too high voltage or too fast weld speed, causing melting at the 
top edge. 
 High arc voltage. 
 Wrong electrode angle or too large electrode. 
 Using the wrong filler metal. 
 Incorrect selection of shielding gas. 
 
Remedies for Undercut 
 Reduce travel speed and power input. 
 Lower the arc voltage or reduce the arc length. The voltage should 
typically be between 15 to 30 volts. The welding arc length should 
not be more than the diameter of the electrode core. 
 Keep the electrode angle between 30 to 45 degrees on the standing 
leg. 
 Use the proper gas mixture based on metal type and thickness. 
 Weld in flat positions. 
 
4. Porosity 
 
Also known as wormhole welds, porosity defects occur when there is an 
entrapment of air or gas bubbles in the weld. The welding process often 
generates gases like hydrogen, carbon dioxide, and steam. A cross-section 
of porous weld beads often resembles a sponge with an accumulation of 
trapped air bubbles. 
The entrapped gases may be localized in a specific location or uniformly 
distributed in the weld. These gas bubbles can weaken the joint of the 
weld metal, predisposing them to fatigue and damage. Depending on their 
formation, these orbital welding errors can occur as: 
 
 
 Gas Porosity. This is a small, spherical-shaped cavity generated 
from trapped gases. The various forms include surface pores, 
elongated cavities, linear porosity, etc. 
 Worm Holes. These are elongated or tubular cavities formed during 
the solidification of trapped gases. You can see them as single holes 
or a group of holes throughout the weld surface. 
 Surface Porosity. This is a kind of porosity that breaks the surface 
of the weld metal. 
 
Causes of Porosity 
 
 Inadequate coating of electrode or use of corroded electrode. 
 Presence of grease, oil, water, rust, or hydrocarbon on the weld 
surface. 
 Using incorrect shielding gas. 
 Too high arc voltage or gas flow. The voltage should typically be 
between 15 to 30 volts. 
 Poor surface treatment of base metal. 
 
Remedies for Porosity 
 
 Choose the suitable electrode and filler material. 
 Ensure proper cleaning of the base metal and prevent pollutants 
from entering the welding area. 
 To enhance the welding process and facilitate gas escape, adjusting 
the welding speed is crucial, as it varies across different welding 
techniques. For example, MIG welding is most effective at a travel 
speed of 14 to 19 inches per minute (IPM), while TIG welding 
achieves optimal results at a slower pace of 4 to 6 IPM. 
 Configure the gas flow meter to the correct flow settings. Depending 
on the welding technique, the gas flow should be between 22 to 30 
cubic feet per hour (CFH). 
 
 
5. Spatter 
 
Spatters consist of metal particles expelled from the welding arc, 
commonly found in ARC, GAS, and tack welding processes. They can 
also appear, though less frequently, in MIG welding. These particles 
typically adhere along the weld bead or within joint designs, marking a 
distinct type of welding defect. 
Spatters that accumulate in the nozzle may detach and damage the weld 
bead. They can also cause accidents for handlers if the spatter projections 
are sharp. 
 
Causes of Spatter 
 Too low voltage and too high amperage current settings. 
 Wrong choice of shielding gas. 
 Rigid electrode working angle. 
 Using a wet electrode and a larger arc length. 
 Contamination of metal surface. 
 
Remedies for Spatter 
 Use the right polarity and adjust the weld current. 
 Use the proper shield gas. 
 Increase electrode angle and decrease arc length. 
 Clean the metal surface before welding. 
 
6. Overlap 
 
 
A weld overlap is a defect where the filler material at the weld’s toe covers 
the metal without bonding. In this case, the weld pool flows excessively 
and extends beyond the toe. The weld metal forms an angle below 90 
degrees when this condition happens. 
 
Causes of Overlap 
 Using the wrong welding technique. 
 Varying electrode angle. 
 Employing large-sized electrodes. 
 High welding current or heat input. 
 
Remedies for Overlap 
 Choose the proper welding technique for optimal arc length. 
 Maintain the right electrode angle. 
 Avoid using large-sized electrodes. 
 Try to weld in flat positions. 
 Use low heat input or welding current. 
 
7. Lamellar Tearing 
 
Lamellar tearing welding fault usually occurs at the bottom of 
welded rolled steel plates. Their distinguishing feature is a crack with a 
terraced appearance. Lamellar tearing occurs when there is a thermal 
contraction within the steel plate. It can also be found outside heat-
affected zones, often parallel to weld fusion boundaries. 
 
Causes of Lamellar Tearing 
 Weld metal deposits on surfaceswith optimum cohesion. 
 Improper material selection and welding orientation. 
 
Remedies for Lamellar Tearing 
 Ensure welding is done at the end of the fabrication. 
 Select the best quality materials and use the right welding 
orientation. 
8. Slag Inclusion 
Slags, hazardous byproducts, emerge in various processes such as 
shielded metal arc, stick, flux-core arc, and submerged arc techniques. 
They often appear as trapped impurities within or on the surface of the 
welded areas. 
 
 
Source from: leniran.blogspot.com 
They occur when you use a flux (solid shielding material) during welding. 
When the flux melts on the surface of the weld or within the weld region, 
these weld defects can occur. The presence of slags affects the metal’s 
weldability and toughness. As a result, they decrease the structural 
performance of the weld. 
 
Causes of Slag Inclusions 
 Incorrect electrode angle. 
 Using very small welding current density. 
 Allowing the weld to cool too fast. 
 Improper cleaning of previous weld layers. 
 Insufficient space for puddles of molten welds. 
 Too fast welding speed. 
 
Remedies for Slag Inclusions 
 Adjust the electrode angle and travel rate. 
 Increase the current density to the appropriate value. 
 Prevent rapid cooling. 
 Clean weld bed surfaces before depositing the next layer. 
 Redesign joints to ensure there is sufficient space for the proper use 
of a puddle of molten welds. 
 Ensure optimal welding speed. 
 
9. Incomplete Fusion 
 
 
 
Also known as lack of fusion, this weld defect occurs due to inaccurate 
welding that results in unfilled gaps. It may be a result of the following: 
 Lack of fusion between the parent metal and the weld metal at the 
weld’s root. 
 Lack of sidewall fusion between parent metal and weld metal at the 
sidewall weld. 
 Lack of inter-run fusion between adjacent layers of weld metals 
during multi-run welding. 
Although this is an internal welding defect, you can also see incomplete 
fusion in welding on the outer surface. This happens when there is an 
improper fusion of the outer sidewall with the parent metal. 
 
Causes of Incomplete Fusion 
 Low heat input. 
 Contamination of the metal surface. 
 Using incorrect electrode diameters for the specific material 
thickness. 
 Too fast travel speed. 
 Large weld pools moving ahead of the arc. 
 
Remedies for Incomplete Fusion 
 Use proper heat input. 
 Clean the welding area and metal surface before welding. 
 Choose the right electrode diameter that fits the material thickness. 
 Optimize the travel speed. 
 Use an adequate weld pool that does not flood the arc. 
 
10. Incomplete Penetration 
Source from: mechasource.blogspot.com 
In welding, penetration is the distance from the upper surface of the base 
metal to the maximum weld extent. Incomplete penetration occurs when 
the metal groove is too narrow and is not filled. As a result, the weld metal 
does not entirely spread through or get to the bottom of the weld joint. 
This reduces the strength of the weld joint and causes weld failure. 
 
Causes of Incomplete Penetration 
 Improper joint alignment. 
 Having too much space between the welds. 
 Moving the welding bead too fast, results in little disposition of 
metal. 
 Using too low amperage setting, preventing adequate melting of 
metal. 
 Incorrect positioning of the electrode. 
Remedies for Incomplete Penetration 
 Use the correct joint geometry and proper alignment. 
 Ensure enough weld metal deposition. 
 Use proper amperage setting. 
 Reduce the arc travel speed. 
 Ensure accurate positioning of electrodes. 
 
11. Distortion 
 
Source from: designlooter.com 
 
Distortion arises from the excessive heat applied during welding, leading 
to changes in the position and dimensions of metal plates. This defect is 
more pronounced in thinner plates, as their limited surface area hampers 
effective heat dissipation. 
 
Causes of Distortion 
 Varying temperature gradients during welding. 
 Using an incorrect welding order. 
 Slow arc travel speed. 
 Too many welds pass with small diameter electrodes. 
 High residual stress in the metal plate to be welded. 
 
Remedies for Distortion 
 Stick to an appropriate temperature gradient for welding. 
 Use correct welding orders. 
 Maintain an arc travel speed of 10 to 20 inches per minute for 
rotating workpieces, and 4 to 10 inches per minute for orbital 
welding equipment. 
 Optimize the design for your sheet metal part for an adequate 
number of weld passes. 
 Use the right amount of weld metal to decrease contraction forces. 
 
12. Burn Through 
 
When there is an application of excessive heat during welding, the process 
may blow holes through the center of the metal. This type of weld defect 
is what we call a burn-through. It’s a common welding defect for thin 
metal sheets with less than 1/4-inch thickness. It may also occur with 
thicker metal stocks if the welding settings are too high or the torch 
movement is too slow. 
 
Causes of Burn Through 
 Too high welder settings for thick metal stocks. 
 Significantly large gaps between metal pieces. 
 The too-slow movement of the torch. 
 Using incorrect wire sizes. 
 
Remedies for Burn Through 
 Avoid using too high a current or welder setting. 
 Prevent having excessive gaps between metal plates. 
 Optimal travel speed is key: for MIG welding, maintain 14 to 19 
inches per minute, while orbital welding equipment should operate 
at 4 to 10 inches per minute. 
 Avoid large bevel angles. 
 Use tight wire sizes. 
 Ensure adequate metal clamping and hold-down. 
13. Mechanical Damage 
 
Mechanical damages, manifesting as indentations on parent metals or 
welds, often arise from mishaps in the welding process. These issues can 
stem from incorrect selection of welding techniques or improper use of 
welding tools. 
 
Causes of Mechanical Damage 
 Incorrect handling of electrode holders. 
 Applying additional force during chipping. 
 Inefficient grinder usage. 
 Failure to engage the arc to the metal. 
 
Remedies for Mechanical Damage 
 Ensure proper handling of electrode holder after welding. 
 Operate welding tools professionally. 
 If required, hammering should be moderate. 
 Engage the arc before welding. 
 
14. Excess Reinforcement 
 
This weld defect occurs due to too much filler material in the weld joint. 
Excess reinforcement can occur as narrow, steep-side beads. It is usually 
a result of insufficient flux coating on the feed wire. Furthermore, the 
excess reinforcement can be ragged and uneven – mountain range 
reinforcement. In this case, the defect occurs due to excess flux or uneven 
travel speed. 
 
Causes of Excess Reinforcement 
 Insufficient or excess flux on the feed wire. 
 Too fast or uneven feed wire travel speed. 
 Varying voltage settings. 
 Leaving large gaps between weld pieces. 
Remedies for Excess Reinforcement 
 Keep the torch moving at a proper speed. 
 Set amperage correctly and prevent excess heat. 
 Adjust voltage to ensure it is optimal. 
 Align the weld pieces to prevent large gaps. 
 
15. Whiskers 
 
Whisker defects are short-length electrode wires sticking out of the weld 
on the root side of the weld joint. They result from a protruding electrode 
wire from the weld pool’s leading edge. 
These electrode wires compromise the aesthetic quality and mechanical 
properties of the weld. For example, whiskers are often seen as inclusions 
that weaken weld joints. They may inhibit the flow or cause equipment 
damage when used for piping applications. 
 
Causes of Whiskers 
 Using a high feed speed for electrode wire. 
 Excessive travel speed. 
 
Remedies for Whiskers 
 Reduce the feed speed of the electrode wire. 
 Ensure the travel speed remains optimal; avoid going too fast. 
 
16. Misalignment 
 
This welding defect occurs when the filler material decomposes in the 
welded joint. It is the difference betweenthe external and/or internal 
heights of weld metal and base metal. You may see it as wavy or curvy 
spots on the weldment’s surface. A misalignment defect weakens the weld 
and reduces its ability to cope in high-fatigue environments. 
 
Causes of Misalignment 
 The too-rapid welding process. 
 Improper choice of technique or handling. 
 Inadequate placement of welding wire. 
 
Remedies for Misalignment 
 Apply a steady but efficient welding process. 
 Use skilled experts and conduct adequate checks before welding. 
 Keep the welding wire in the right position. 
 
How to Detect Invisible Welding Defects: Non-Destructive 
Weld Testing and Inspections 
 
Since welding involves the fusion of two or more metals, it may be 
difficult to detect internal welding defects using visual inspection. In this 
case, non-destructive testing (NDT) is a valuable option as it will show 
you the integrity of your weld. This process will keep the operations 
running smoothly without damaging any tools. 
 
Magnetic Particle Inspection 
 
This is one of the best methods of detecting surface cracks and weld 
defects that are too small to be detected by visual inspection. It is also an 
excellent choice for subsurface discontinuities in a weld. The process of 
electromagnetic particle inspection involves magnetizing the workpiece. 
It then uses a fluorescent solution to highlight the defects for proper 
documentation. 
 
Ultrasonic Inspection 
 
This inspection method uses high-frequency sound waves to check the 
interior and exterior of welded metals. It not only discovers defects and 
discontinuities in the weld but also measures the exact position of the 
defects. The instrument transmits high-frequency beams into the metal. 
Once it detects a weld defect, it bounces back to the ultrasonic 
welding machine to give a clear picture of a potential defect and its 
location. This allows for quick and easy fixing of the fault. 
Radiographic Inspection 
 
This technique is adaptable to various situations. It uses gamma rays or x-
rays to inspect the interior of welds. The setup is simple and fast, 
presenting a vivid picture of defects on the screen of the X-ray machine. 
 
Prevention of welding defects 
 
Preventing welding defects involves a multi-pronged approach that 
focuses on proper preparation, technique, and material selection. Here are 
some key strategies: 
 
Pre-Weld Preparation: 
 
Cleanliness: This is crucial. Thoroughly clean the weld area to remove 
any contaminants like rust, oil, paint, or moisture. These can vaporize 
during welding and become trapped as gas bubbles or promote hydrogen 
cracking. 
 
Joint Design and Fit-up: The joint design should be appropriate for the 
materials and application. Ensure proper fit-up of the pieces to be welded 
using clamps or fixtures. Poor fit-up can lead to uneven heating, 
distortion, and cracking. 
 
Material Selection: Choose the right filler metal and base metal 
combination for the job. Pay attention to compatibility and strength 
requirements. 
 
Welding Technique: 
 
Welding Parameters: Follow recommended settings for amperage, travel 
speed, and voltage based on the welding process, material thickness, and 
filler metal. Incorrect settings can lead to overheating, undercutting, or 
poor penetration. 
 
Welding Angle and Travel Direction: Maintain the proper torch angle and 
travel direction to ensure good weld penetration and prevent defects like 
undercutting or incomplete fusion. 
 
Shielding Gas: Use the appropriate shielding gas for the material being 
welded and maintain proper gas flow rate to protect the weld pool from 
atmospheric contamination. 
 
Consumables and Equipment: 
 
Electrode/Filler Metal Storage: Store electrodes and filler metals properly 
according to manufacturer recommendations to prevent moisture pick-up, 
which can lead to hydrogen porosity. 
 
Equipment Maintenance: Maintain your welding equipment in good 
working order. Faulty torches, worn tips, or malfunctioning feeders can 
contribute to poor weld quality. 
 
Inspection and Post-Weld Procedures: 
 
Visual Inspection: Inspect the weld after completion for any surface 
irregularities or signs of cracking. 
Non-Destructive Testing (NDT): For critical welds, consider using NDT 
methods like radiographic or ultrasonic testing to detect internal defects. 
 
Post-Weld Heat Treatment: In some cases, post-weld heat treatment may 
be necessary to reduce residual stresses and improve the toughness of the 
weld joint. 
 
Additional Tips: 
 
Welder Training and Qualification: Ensure welders are properly trained 
and qualified in the specific welding process they are using. 
 
Welding Procedure Specifications (WPS): Follow established welding 
procedure specifications (WPS) that outline the proper procedures and 
parameters for the specific weld joint. 
 
Practice: Regular practice on scrap material helps welders develop good 
technique and identify potential issues before working on critical welds. 
 
 
Conclusion 
 
By following these practices, welders can significantly reduce the risk of 
welding defects and produce high-quality, strong welds. 
Welding defects are a major issue in various industries, affecting the 
integrity and performance of welded structures. Causes include material-
related issues and human errors, necessitating comprehensive quality 
control measures. Common defects include porosity, lack of fusion, 
undercutting, incomplete penetration, and cracking. Detecting defects 
through non-destructive testing is crucial. Preventing defects requires a 
holistic approach, including material selection, welding procedure 
development, joint preparation, shielding, equipment maintenance, and 
skilled workforce training. 
 
References 
 
 Understanding weld discontinuities 
https://weldinganswers.com/434/ 
 
 Types of Weld Discontinuities and How to Correct Them 
https://weldinganswers.com/434/ 
 
 https://swantonweld.com/welding-inspection-defects-
discontinuities/#:~:text=A%20Welding%20Discontinuity,Unaccep
table%20profiles 
 
 https://www.codeaweld.com/how-to-prevent-welding-defects/ 
 
 Welding Defects. (2005). Classification of cracks to DIN 8524 Part 
3. ISF: Aachen. 
 
 Lucas, B., Mathers, G., & Eileens, C. Defects/imperfections in 
welds—slag inclusions, Job Knowledge 43, The Welding Institute. 
 
 NDT Resource Centre. https://www.nde-ed.org/index_flash.htm. 
 
 © Springer Nature Singapore Pte Ltd. 2017 N.R. Mandal, Ship 
Construction and Welding, Springer Series on Naval Architecture, 
Marine Engineering, Shipbuilding and Shipping 2, DOI 
10.1007/978-981-10-2955-4_20 
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