8.1 State TWO aspects to check when doing a visual inspection on welded joints - NSC Mechanical Technology Welding and Metalwork - Question 8 - 2023 - Paper 1
Question 8
8.1 State TWO aspects to check when doing a visual inspection on welded joints.
8.2 State ONE property that is tested when conducting a free-bend test on a welded j... show full transcript
Worked Solution & Example Answer:8.1 State TWO aspects to check when doing a visual inspection on welded joints - NSC Mechanical Technology Welding and Metalwork - Question 8 - 2023 - Paper 1
Step 1
State TWO aspects to check when doing a visual inspection on welded joints.
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Answer
Shape of the profile - Ensure that the weld maintains the required geometric form.
Uniformity of the surface - Check for evenness and consistency in the weld appearance.
Step 2
State ONE property that is tested when conducting a free-bend test on a welded joint.
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Answer
Ductility - This property measures the ability of the welded joint to deform without breaking under tensile stress.
Step 3
Define weld defect.
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A weld defect is a flaw that does not meet the prescribed requirements of a welded joint, which may lead to potential failure.
Step 4
State TWO causes of the following weld defects: 8.4.1 Undercutting
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Current too high - Excessive electrical current can lead to the erosion of material.
Too low arc voltage - Insufficient voltage can create an uneven weld profile.
Step 5
State TWO causes of the following weld defects: 8.4.2 Blow hole
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Presence of contaminants - Impurities on the surface can lead to porosity in the weld.
Use of wet electrode - Moisture in electrodes can introduce gas into the weld.
Step 6
Name TWO examples of destructive tests done on welded joints.
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Nick break test - A test that measures the weld's ability to withstand physical stress.
Guided bend test - This test assesses the flexibility and integrity of the weld under bending conditions.
Step 7
Explain how to conduct an X-ray test on a welded joint.
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Preparation: Seal the photographic film in an envelope and place it behind the object.
Testing process: Use an X-ray source directed at the joint and step behind protective shielding.
Exposure: Activate the source briefly; X-rays penetrate the joint and film.
Evaluation: Analyze the resulting film for any imperfections.
Step 8
Name the TWO types of dyes that can be used for a liquid dye penetration test.
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Fluorescent dye - This dye illuminates under UV light, revealing defects.
Brightly coloured dye - This dye visually highlights surface flaws.
Step 9
State TWO examples of internal weld defects.
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Cracks - Internal fractures that can compromise structural integrity.
Lack of fusion - Failure of the weld to bond properly with the base material.
Step 10
State TWO methods of reducing centre-line cracks.
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Reduce the heat input - Lowering the welding temperature helps minimize thermal stresses.
Control the cooling rate - Slower cooling can prevent rapid contraction and mitigate cracking.
