3.1 Why is tempering of steel done after hardening?
3.2 Give ONE reason for EACH of the following heat-treatment processes on steel:
3.2.1 Case hardening
3.2.2 Annealing
3.3 Explain how to conduct a spark test to identify the type of steel - NSC Mechanical Technology Welding and Metalwork - Question 3 - 2023 - Paper 1
Question 3
3.1 Why is tempering of steel done after hardening?
3.2 Give ONE reason for EACH of the following heat-treatment processes on steel:
3.2.1 Case hardening
3.2.2 Anne... show full transcript
Worked Solution & Example Answer:3.1 Why is tempering of steel done after hardening?
3.2 Give ONE reason for EACH of the following heat-treatment processes on steel:
3.2.1 Case hardening
3.2.2 Annealing
3.3 Explain how to conduct a spark test to identify the type of steel - NSC Mechanical Technology Welding and Metalwork - Question 3 - 2023 - Paper 1
Step 1
Why is tempering of steel done after hardening?
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Answer
Tempering of steel after hardening is essential to relieve internal stresses and to reduce brittleness. This process enhances toughness, making the steel less prone to fractures while maintaining its hardness.
Step 2
Give ONE reason for EACH of the following heat-treatment processes on steel: Case hardening
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Answer
Case hardening is performed to obtain a wear-resistant surface while ensuring the core remains strong and tough enough to withstand applied loads.
Step 3
Give ONE reason for EACH of the following heat-treatment processes on steel: Annealing
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Answer
Annealing is done to relieve internal stresses in the steel, soften the material, and increase its ductility, making it easier to work with during further machining processes.
Step 4
Explain how to conduct a spark test to identify the type of steel.
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Answer
To conduct a spark test, hold the steel against a grinding wheel. Observe the spark pattern produced to identify the type of steel, as different steels produce distinct spark characteristics.
Step 5
Explain how you will conduct the following tests: Filing test
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Answer
For the filing test, file on the tip or near the edge of the material. The bite taken by the file will indicate the hardness of the steel.
Step 6
Explain how you will conduct the following tests: Bend test
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Answer
In the bend test, subject the metal to deformation by bending it. Observe the rupture point of the metal to evaluate its ductility and toughness.
Step 7
What sound do the following materials make when performing a sound test? Low-carbon steel (LCS)
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Answer
Low-carbon steel (LCS) produces a dull (low pitch) sound during a sound test.
Step 8
What sound do the following materials make when performing a sound test? High-carbon steel (HCS)
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Answer
High-carbon steel (HCS) produces a loud and clear (high pitch) sound during a sound test.
