Types of welding Defects

In this article, we are going to Explain What is welding defects ? Different Types Of Welding Defects.

Types of welding defects

What is welding defects ?

Welding defects are flaws or imperfections that occur during the welding process, resulting in welds that do not meet the desired quality or specifications. These defects can compromise the strength, integrity, and performance of the welded joint.

They can take various forms, such as porosity, lack of fusion, incomplete penetration, cracks, undercut, and spatter. Detecting and addressing these defects is crucial to ensure the quality and reliability of welded structures and components. By understanding the different types of welding defects and their causes, proper measures can be taken to prevent or rectify them, ensuring the durability and safety of welded joints.

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types of welding defects

These are the following types of welding defects;

  1. Porosity and Blowholes
  2. Undercut
  3. Weld crack
  4. Incomplete fusion
  5. Slag inclusion
  6. Incomplete penetration
  7. Spatter
  8. Distortion
  9. Hot Tear
  10. Mechanical damage
  11. Misalignment
  12. Excess reinforcement
  13. Overlap
  14. Lamellar tearing
  15. Whiskers

1. porosity

Porosity refers to the presence of small cavities or voids within a material. In the context of welding, porosity specifically refers to the formation of gas pockets or bubbles within the weld metal. These gas pockets are typically trapped during the solidification process when the molten metal cools and hardens.

Porosity welding defects

Porosity in welding can occur due to various reasons, including the presence of moisture, oil, or other contaminants on the surfaces being welded, inadequate shielding gas coverage, improper gas flow rate, or the use of contaminated filler materials. These factors can lead to the entrapment of gases, such as hydrogen, nitrogen, or oxygen, in the weld pool.

The presence of porosity in a weld can weaken its mechanical properties and reduce its load-carrying capacity. The size, shape, and distribution of the gas pockets can vary, ranging from small spherical voids to elongated or irregularly shaped cavities. Porosity is often visually identifiable upon inspection of the weld, appearing as tiny holes or irregularly shaped voids.

To prevent porosity, it is crucial to ensure proper cleaning and preparation of the welding surfaces, effective gas shielding, appropriate gas flow rates, and the use of clean and uncontaminated filler materials. Welding parameters, such as heat input and travel speed, should also be carefully controlled. By addressing these factors, welders can minimise the occurrence of porosity and ensure the integrity and strength of the welded joint.

Causes of PorosityRemedies and Prevention
1.Contaminated Base MetalThoroughly clean and remove any contaminants from the welding surfaces. Ensure proper storage and handling of base metals to prevent contamination.
2.Contaminated Filler MaterialUse clean and uncontaminated filler materials. Store and handle filler materials properly to avoid moisture or dirt absorption.
3.Inadequate Shielding Gas CoverageEnsure proper shielding gas flow rate and coverage over the weld zone. Adjust shielding gas flow according to welding parameters and joint configuration.
4.Moisture or Oil PresenceEliminate moisture or oil on the welding surfaces through proper cleaning and preheating. Use proper degreasing methods and avoid excessive humidity in the welding environment.
5.Incorrect Welding ParametersOptimize welding parameters such as current, voltage, travel speed, and heat input to achieve the appropriate weld puddle and solidification conditions.
6.Insufficient Gas FlowEnsure adequate gas flow rate to shield the weld pool effectively. Check for gas leaks in the welding system and adjust flow rate as per the specifications.
Causes and Remedies of porosity

2. undercut

Undercut is a welding defect characterized by a groove or depression formed along the weld toe or root. It typically occurs on the base metal adjacent to the weld and is often caused by excessive heat or improper manipulation of the welding electrode.

Undercut welding defects

During the welding process, if excessive heat or incorrect manipulation of the welding electrode occurs, it can result in the removal of excess molten metal from the weld area. This removal causes a groove or depression along the edges of the weld joint, creating an undercut.

Causes of Undercut in WeldingRemedies for Undercut in Welding
Excessive heat inputReduce welding current or voltage
Improper electrode angleAdjust electrode angle to maintain proper arc coverage
Excessive travel speedSlow down the welding speed
Incorrect electrode sizeUse an appropriate electrode size for the specific welding application
Insufficient filler materialIncrease the deposition rate of filler material
Incorrect joint preparationEnsure proper joint preparation, including bevel angle and edge preparation
Excessive weaving or oscillationMaintain consistent and controlled weaving motion
Insufficient shielding gas coverageOptimize shielding gas flow rate and ensure proper gas coverage

3. Weld crack

In welding, a weld crack refers to a fracture or separation that occurs in the welded joint or adjacent base metal.

Weld crack defects

Weld cracks are a significant type of welding defect that can occur during the welding process. There are different types of weld cracks, including:

  1. Hot Cracks: Hot cracks, also known as solidification cracks, occur during the solidification of the weld metal. They are typically caused by the presence of impurities, high cooling rates, or a metallurgical incompatibility between the base metal and the filler material. Hot cracks can develop in the partially solidified weld metal or in the heat-affected zone (HAZ).
  2. Cold Cracks: Cold cracks, also called hydrogen-induced cracking or delayed cracking, appear after the welding process. They are caused by the presence of hydrogen in the weld metal, high residual stresses, or a combination of both. Cold cracks often occur in highly restrained joints and can propagate through the weld metal or the base metal.
  3. Stress Cracks: Stress cracks are a result of excessive tensile stress in the welded joint. They can occur during or after welding due to factors such as inadequate joint design, improper welding techniques, or improper welding sequence. Stress cracks typically manifest as longitudinal cracks in the weld or the adjacent base metal.
  4. Lamellar Cracks: Lamellar cracks are a type of cracking that occurs in layered or laminated materials, such as clad plates. They develop along the interfaces between the layers due to differences in mechanical properties or residual stresses.
Causes of Weld CracksRemedies for Weld Cracks
High cooling rate during weldingControl cooling rate by using preheating or post-weld heat treatment techniques.
Excessive stress on the welded jointAnalyze and address the source of excessive stress, such as improper joint design, inadequate reinforcement, or improper welding sequence.
Inadequate filler material selectionUse filler materials with appropriate mechanical properties and compatibility with the base metal.
Presence of impurities or contaminants in the weldEnsure proper cleaning of base metal and filler material before welding. Use clean shielding gases and fluxes.
Incorrect welding parametersOptimize welding parameters such as heat input, current, voltage, and travel speed to ensure proper fusion and minimize thermal stresses.
Insufficient or improper weld preparationProperly prepare the joint by ensuring proper bevel angle, edge alignment, and removal of contaminants or oxides.
Inadequate preheatingImplement preheating to minimise thermal stress and improve weldability, especially for materials prone to cracking.
Incompatible base metal and filler metal combinationUse filler metals that are compatible with the base metal to ensure proper fusion and prevent cracking.
Insufficient weld reinforcement or improper joint designEnsure proper weld reinforcement and joint design to distribute stress evenly and avoid stress concentration points.
Inadequate weld quality control and inspectionImplement thorough weld quality control measures, including visual inspection, non-destructive testing, and adhering to relevant welding standards and procedures.

It’s important to note that the specific causes and remedies for weld cracks may vary depending on the welding process, materials being welded, and the specific application.

4. Incomplete Fusion

Incomplete fusion in welding

Incomplete fusion, also known as lack of fusion, refers to a welding defect where there is inadequate bonding or fusion between the weld metal and the base metal or between different layers of the weld. In an ideal weld, the molten filler metal should fuse completely with the base metal, creating a sound and continuous joint.

Causes of Incomplete FusionRemedies for Incomplete Fusion
Insufficient heat inputIncrease heat input by adjusting the welding parameters, such as increasing the welding current or slowing down the travel speed. Ensure proper preheating of the base metal if required.
Incorrect electrode positioningMaintain proper electrode angle and alignment to ensure adequate contact with both the base metal and the weld metal. Use appropriate welding techniques to ensure proper fusion.
Improper joint preparationEnsure proper cleaning and preparation of the joint surfaces. Remove any contaminants or oxide layers that may hinder fusion. Use appropriate bevel angles and edge preparations for the joint.
Inadequate interpass temperatureMaintain proper interpass temperature during multi-pass welding. Use preheating or post-heating methods to ensure sufficient heat between passes for proper fusion.
Incompatible filler metalSelect a filler metal that is compatible with the base metal and has similar melting and solidification characteristics. Ensure proper filler metal selection to achieve good fusion.
Insufficient weld metal depositionIncrease the amount of weld metal deposition by adjusting the welding technique or increasing the size of the weld bead. Ensure proper filler metal selection and feeding to achieve adequate fusion.

5. slag inclusion

Slag inclusion in welding

Slag inclusion is a welding defect that occurs when non-metallic materials, known as slag, become trapped in the weld metal during the welding process. Slag is a byproduct of the welding flux or the protective coating on the electrode. It consists of impurities, oxides, and other substances that are not part of the desired weld composition.

Causes of Slag InclusionRemedies for Slag Inclusion
1. Insufficient cleaning of the base metal surface1. Thoroughly clean and remove any contaminants, such as dirt, rust, or scale, from the welding area before starting the weld. Proper surface preparation helps prevent the entrapment of slag.
2. Excessive use of flux or improper flux application2. Use the appropriate amount of flux and ensure even distribution. Follow the recommended flux application techniques to avoid excess buildup.
3. Incorrect welding technique or improper electrode angle3. Use the correct welding technique, such as maintaining the appropriate travel speed and electrode angle. Proper manipulation of the electrode ensures proper fusion and minimizes slag entrapment.
4. Insufficient shielding gas coverage or gas flow rate4. Ensure adequate shielding gas coverage, especially for gas shielded welding processes. Adjust the gas flow rate according to the welding requirements. Proper gas coverage helps prevent slag from being trapped in the weld.
5. Incorrect electrode or filler material selection5. Choose the appropriate electrode or filler material that is compatible with the base metal and welding process. Using the correct consumables helps achieve better fusion and reduces the risk of slag inclusion.
6. Excessive heat input or improper welding parameters6. Control the heat input and welding parameters, such as voltage, current, and travel speed, within the recommended range. Adjustments should be made to achieve proper fusion without overheating the weld, which can lead to slag inclusion.

6. incomplete penetration

Incomplete penetration in welding

Incomplete penetration in welding refers to a welding defect where the weld metal does not fully penetrate the joint or reach the root of the weld. It occurs when the depth of fusion is insufficient, resulting in an incomplete connection between the base metal pieces.

Causes of Incomplete PenetrationRemedies
Insufficient heat inputIncrease heat input by adjusting welding parameters such as current, voltage, or travel speed. Ensure proper preheating if necessary.
Incorrect welding techniqueEnsure proper welding technique, including correct electrode angle, manipulation, and travel speed. Maintain proper arc length and electrode position.
Improper joint preparationEnsure proper joint design and preparation, including appropriate joint clearance, bevel angle, and root face. Ensure sufficient access to the root of the joint.
Inadequate weld sizeIncrease weld size by adjusting the number of passes or using larger diameter electrodes or filler material.
Inappropriate welding processEvaluate and select the appropriate welding process that allows for better penetration, such as using a different welding method or variant.
Incompatible base metal or filler materialEnsure compatibility between the base metal and filler material, including their composition and mechanical properties. Select appropriate filler material to enhance penetration.
Obstructed root accessRemove any obstructions or contaminants that may hinder the proper access and flow of the weld metal to the root of the joint.
Insufficient joint fit-upEnsure proper alignment and fit-up of the joint, including maintaining the appropriate gap and root opening. Properly tack weld the joint to secure alignment.

7. spatter

Spatter in welding

Spatter in welding refers to the small droplets of molten metal that are expelled from the welding arc during the welding process accumulate on the base metal throughout the weld bead along its length. These droplets can land on surrounding surfaces, equipment, or even the weld itself.This is particularly common happens in gas-metal arc welding.

Causes of SpatterRemedies for Spatter
Excessive current or voltage settingsAdjust the welding parameters within the recommended range
Incorrect wire feed speedEnsure proper wire feed speed as per the welding process
Improper shielding gas flow or coverageOptimize shielding gas flow rate and ensure proper gas coverage
Contaminated base metal or filler materialClean and prepare the welding surfaces thoroughly
Poor contact tip or liner conditionReplace or repair faulty contact tips or liners
Wire feed issues, such as birdnesting or kinksAddress wire feed problems, ensure smooth wire delivery
Inappropriate stick-out lengthMaintain proper stick-out length for the welding process
Electrode or wire diameter mismatchUse the appropriate electrode or wire diameter for the welding application
Inadequate or improper nozzle positioningPosition the welding nozzle correctly for optimal gas coverage
Excessive spatter buildup on contact tipClean or replace the contact tip regularly

8. Distortion

Distortion in welding

Distortion, in the context of welding, refers to the deformation or changes in shape that occur in a workpiece or structure as a result of the welding process. When metals are heated during welding, they expand due to thermal expansion. As the weld cools down, it undergoes contraction, which can cause the material to shrink and distort.

Causes of Distortion in WeldingRemedies for Distortion
Uneven heating and cooling of the weld metal and surrounding base metalPreheat the base metal to reduce temperature gradients. Use welding techniques that minimize heat input and control the cooling rate. Employ heat sinks or fixtures to dissipate heat evenly.
Improper joint fit-up or alignmentEnsure proper fit-up and alignment of the joint prior to welding. Use appropriate clamping or fixturing to hold the components in place during welding.
Welding sequence and directionImplement balanced welding sequences to distribute the weld-induced stresses evenly. Employ backstep or skip welding techniques to minimize cumulative distortion.
Inadequate tack welds or inadequate weld sizeEnsure sufficient tack welds to securely hold the joint in place during welding. Use the correct welding parameters to achieve adequate weld size and penetration.
Insufficient weld joint preparationProperly clean and prepare the joint surfaces before welding. Bevel or chamfer the edges as necessary to promote better weld penetration and reduce residual stress.
Welding technique and parametersUse welding techniques that minimize heat input, such as pulsed or low-heat welding methods. Optimize welding parameters, including travel speed, current, and voltage, to reduce heat input and control distortion.
Material selectionSelect materials with lower coefficients of thermal expansion or utilize prequalified welding procedures for specific materials. Consider using distortion-resistant alloys or cladding techniques.
Welding fixtures and jigsImplement appropriate fixtures, clamps, or jigs to hold the components securely in position during welding. Use heat sinks or backing bars to control cooling rates and limit distortion.
Welding sequence and directionImplement balanced welding sequences to distribute the weld-induced stresses evenly. Employ backstep or skip welding techniques to minimize cumulative distortion.
Post-welding treatmentsApply stress-relief techniques, such as heat treatment or mechanical stress relief, to alleviate residual stresses and minimize distortion.

9. Hot tear

Hot tearing, also known as solidification cracking, is a welding defect that occurs during the cooling and solidification of the weld metal. It is characterised by the formation of cracks or fractures in the weld bead or nearby areas while the metal is still in a partially molten state.

Causes of Hot Tear in WeldingRemedies for Hot Tear in Welding
High restraint in the jointUse preheating or post-weld heat treatment to reduce residual stresses
Insufficient joint design or inadequate fit-upEnsure proper joint design and adequate fit-up to accommodate for shrinkage
Excessive weld metal restraintUse appropriate welding techniques, such as backstep welding or peening, to reduce restraint
Inadequate filler metal ductility or compositionSelect filler metals with suitable ductility and composition for the specific application
Improper welding parameters (e.g., excessive heat input)Optimize welding parameters to minimize thermal stresses and control cooling rates
Inadequate preheating or interpass temperature controlApply proper preheating and interpass temperature control to prevent rapid cooling and thermal gradients
Poor weldability of the base materialChoose base materials with good weldability and consider pre-qualifying the welding procedure
Insufficient support or clamping of the jointProvide adequate support and clamping to minimize distortion and stress concentration
Improper welding technique or sequencingImplement appropriate welding techniques and sequencing to minimise stress buildup
Inadequate training or skill of the welderEnsure well-trained and skilled welders perform the welding operations

10. Mechanical Damage

Mechanical damage in welding refers to the physical harm or injury inflicted on a welded joint or surrounding areas during or after the welding process. It involves the detrimental alteration of the weld or the adjacent materials due to external forces or improper handling.

Causes of Mechanical Damage in WeldingRemedies for Mechanical Damage in Welding
Additional force during chippingMechanical damage can occur due to excessive force applied during the chipping process after welding. | To prevent this, operators should exercise caution and avoid excessive force during chipping. Properly operate the welding tools to avoid damaging the weld.
Incorrect handling of the electrode holderMechanical damage can result from mishandling or dropping the electrode holder onto the welded metal. | After welding, ensure that the electrode holder is securely placed in a safe position to prevent it from falling onto the welded metal and causing damage.
Inefficient use of a grinderMechanical damage can occur if a grinder is used improperly or excessively. | When using a grinder, operators should exercise moderation and use appropriate grinding techniques to prevent excessive material removal and potential damage to the weld.

11. misalignment

Misalignment damage in welding refers to a condition where the alignment of the materials being welded is not properly maintained during the welding process. It occurs when the pieces being joined are not in the correct position, resulting in improper fusion or weld defects.

Causes of Mechanical Damage in WeldingRemedies for Mechanical Damage in Welding
Rapid welding processApply a slower or more controlled welding process to allow for proper alignment.
Unskilled welder or improper checkingEmploy skilled welders who have proper training and experience in maintaining alignment during welding.
Improper placement of welding wireMaintain proper alignment of the welding wire to ensure accurate deposition of weld metal

12. Excess Reinforcement

Excess reinforcement in welding

Excess reinforcement in welding refers to the condition where the weld metal protrudes beyond the surface of the base metal or the desired weld profile. It occurs when the weld bead is larger or taller than necessary, resulting in an excessive buildup of weld metal.

Causes of Excess Reinforcement in WeldingRemedies for Excess Reinforcement in Welding
Over flux or fast/uneven travel speed on the feed wireMaintain a proper and consistent torch travel speed.
More current and heatSet the welding current correctly and avoid overheating.
Varying voltage, mostly lowAdjust the voltage to ensure it is not too low.
Leaving a big gap between the welding piecesAlign the welding pieces

13. Overlap

Overlap in welding

In welding, “overlap” refers to a joint configuration where two or more pieces of material are joined together by overlapping their edges. It is a type of joint design commonly used in various welding processes.

Causes of Overlap in WeldingRemedies for Overlap in Welding
Excessive welding current or voltageAdjust welding parameters to appropriate levels
Improper welding technique or travel speedEnsure proper welding technique and maintain consistent travel speed
Inadequate electrode manipulation or angleImprove electrode manipulation and maintain correct angle
Incorrect joint preparationEnsure proper joint preparation, including cleaning and beveling
Insufficient cleaning of welding surfacesThoroughly clean welding surfaces before welding
Insufficient penetrationIncrease heat input or adjust welding parameters for better penetration
Improper fit-up of the jointEnsure proper fit-up and alignment of the joint before welding
Inadequate welding supervision or trainingProvide proper supervision and training to welders
Welding on dirty or contaminated surfacesEnsure surfaces are clean and free from contaminants before welding
Insufficient gas shielding or gas flow rateVerify proper gas shielding and adjust flow rate as required
Inadequate control of weld pool and molten metalImprove control over the weld pool and molten metal flow

14. Lamellar Tearing

Lamellar tearing, also known as through-thickness cracking, is a type of welding defect that can occur in welded structures, particularly in steel plates or heavy sections. It is caused by the combination of tensile stresses and a susceptible microstructure.

Presence of weld metal deposits on the metal surfaceConduct a welding rest at the end to prevent the occurrence of lamellar tearing
Improper welding orientation and material selectionUse the appropriate welding orientation and select high-quality materials

15. Whiskers

In MIG welding, when the electrode wire extends beyond the leading edge of the weld pool and is fused into the root side of the joint, it is commonly referred to as “whiskers.” Whiskers occur when short lengths of the electrode wire stick out from the weld and become embedded in the weld joint.

Increased electrode wire feed speedReduce the electrode wire feed speed
Excessive travel speedOptimize travel speed and avoid excessive speeds

16. burn through

In welding, “burn-through” refers to a condition where the welding heat causes excessive melting or penetration of the base metal, resulting in a hole or gap in the weld joint. It occurs when the welding process generates too much heat or when the welder fails to control the welding parameters properly.

Excessive heat inputReduce heat input by adjusting welding parameters (lower current, slower travel speed, etc.)
Inadequate joint preparationEnsure proper joint design and preparation to provide sufficient material thickness and fit-up
Insufficient welder skill or techniqueImprove welder training and technique to achieve proper control of heat input and weld penetration
Improper selection of welding processSelect a welding process suitable for the specific material and thickness being welded
Insufficient use of backing bars or backing stripsUtilize appropriate backing bars or strips to provide support and control heat dissipation
Inadequate welding position or techniqueOptimize welding position and technique to prevent excessive heat concentration in a single area
Inconsistent or improper weld sequencingFollow a proper weld sequencing plan to distribute heat evenly and minimize localized overheating
Insufficient welder experience with the materialEnsure welders have sufficient knowledge and experience with the specific material to prevent burn-through

Source: Wikipedia

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