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Questions and Answers
What is a potential consequence of having a bad profile in one pass of a multi-pass weld?
What is a potential consequence of having a bad profile in one pass of a multi-pass weld?
Which of the following is a cause of overlaps or rolls?
Which of the following is a cause of overlaps or rolls?
What is the effect of undercuts on the work?
What is the effect of undercuts on the work?
What is the likely cause of unfilled craters?
What is the likely cause of unfilled craters?
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Which of the following is a cause of burn-through?
Which of the following is a cause of burn-through?
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What is the effect of burn-through on the work?
What is the effect of burn-through on the work?
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What is the primary cause of surface porosity in welding?
What is the primary cause of surface porosity in welding?
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Which of the following metals is most prone to surface oxidation during welding?
Which of the following metals is most prone to surface oxidation during welding?
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What is the primary cause of excessive spatter in welding?
What is the primary cause of excessive spatter in welding?
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What does a bad weld surface appearance typically indicate?
What does a bad weld surface appearance typically indicate?
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What is the primary cause of lack of fusion in welding?
What is the primary cause of lack of fusion in welding?
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What type of defect is often an indication of underlying subsurface porosity?
What type of defect is often an indication of underlying subsurface porosity?
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What type of weld defects are surface cracks categorized under?
What type of weld defects are surface cracks categorized under?
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What is a primary cause of surface cracks in welds?
What is a primary cause of surface cracks in welds?
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What is the result of uneven heating of the workpieces during welding?
What is the result of uneven heating of the workpieces during welding?
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What is the effect of a bad bead profile on a weld?
What is the effect of a bad bead profile on a weld?
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What is a common characteristic of visual or surface weld defects?
What is a common characteristic of visual or surface weld defects?
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What is the category of weld defects that includes lack of fusion and lack of penetration?
What is the category of weld defects that includes lack of fusion and lack of penetration?
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What is the primary factor that determines the performance of welded structures or components in service?
What is the primary factor that determines the performance of welded structures or components in service?
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What is the primary reason for the generation of defects in weldments?
What is the primary reason for the generation of defects in weldments?
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How does the presence of defects in weld joints affect the structure or component?
How does the presence of defects in weld joints affect the structure or component?
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According to IIW, how many groups are weld defects classified into?
According to IIW, how many groups are weld defects classified into?
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What type of defect includes blowholes, porosity, and shrinkage?
What type of defect includes blowholes, porosity, and shrinkage?
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What type of defect includes undercut, underfill, and overlap?
What type of defect includes undercut, underfill, and overlap?
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What is the main cause of lack of fusion in welding?
What is the main cause of lack of fusion in welding?
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Where can subsurface cracks occur in a weld?
Where can subsurface cracks occur in a weld?
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Why are weld cracks considered dangerous?
Why are weld cracks considered dangerous?
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What is the most common location for lack of penetration defects to occur?
What is the most common location for lack of penetration defects to occur?
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What is the effect of increasing arc voltage on lack of penetration?
What is the effect of increasing arc voltage on lack of penetration?
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Why are subsurface cracks more serious in certain service conditions?
Why are subsurface cracks more serious in certain service conditions?
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Study Notes
Weld Defects
- Weld defects can be categorized into two types: surface/visual defects and hidden/subsurface defects.
Surface/Visual Defects
- Surface cracks: the most dangerous defect, caused by high concentration stresses, poor fit-up, and incorrect welding procedures.
- Distortion/Warpage: uneven heating during welding, leading to welding stresses and distortion of the structure.
- Incorrect weld profile: bad bead profiles affect the performance of the weld under load.
- Overlaps or rolls: protrusions of weld metal beyond the bond at the toe, face, or root of the weld, caused by excessive welding current and wrong tilt of the electrode.
- Undercuts: grooves melted into the parent metal, reducing the cross-section of the work and leading to cracking.
- Unfilled craters: sudden interruption of the arc, reducing the cross-section of the weld and acting as a source of crack formation.
- Burn-through: holes burned through the parent metal, caused by excessive root gap, insufficient root face, and excessive welding current.
- Surface porosity: caused by using un-dried covered electrodes or electrodes with expired shelf-life, indicating potential subsurface porosity.
- Excessive spatter: unstable arc, wrong electrode selection, bare electrodes, heavy welding current, and poor technique of the welder.
- Bad surface appearance: bad workmanship, indicative of surface defects that may not be structurally important.
Hidden/Subsurface Defects
- Lack of fusion: incomplete fusion between parent metal and weld metal, or between layers of multi-pass welding, caused by insufficient welding current, electrode offset, high welding speed, and improper procedure.
- Subsurface cracks/hidden cracks: categorized by location (in the weld, HAZ, interface, or base metal), creating a serious reduction in strength and potentially leading to sudden failure.
- Lack of penetration: defect occurring in the root of the weld, caused by decreased welding current, increased arc voltage, and poorly directed arc.
Note: Some slides (IIT TIRUPATI 17-22) did not contain specific information, so they were not included in the summary.
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Description
Test your knowledge on the common defects that can occur in weld joints and their impact on the strength and performance of welded structures. Learn about the main reasons behind these defects and how they can lead to failure. Improve your understanding of welding techniques and best practices.
