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 Automotive - 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 An... 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 Automotive - Question 3 - 2023 - Paper 1
Step 1
Why is tempering of steel done after hardening?
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Answer
Tempering of steel is performed after hardening to relieve strains and brittleness. It increases the toughness of the steel and helps refine its grain structure.
Step 2
Give ONE reason for EACH of the following heat-treatment processes on steel: Case hardening
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Answer
The purpose of case hardening is to obtain a wear-resistant surface while ensuring that the core of the steel remains 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
The main reason for annealing is to relieve internal stresses within the steel, effectively softening it and increasing its ductility.
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 that emanates from the metal to help identify its type.
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 will determine 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, the metal is subjected to deformation by bending. Observe the rupture of the metal to assess its ductility and toughness.
Step 7
What sound do the following materials make when performing a sound test? Low-carbon steel
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Answer
Low-carbon steel 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
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High-carbon steel emits a loud and clear (high pitch) sound when subjected to a sound test.
