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3.1 Name ONE property of steel that is tested by conducting a bending test on steel - NSC Mechanical Technology Automotive - Question 3 - 2018 - Paper 1
Question 3
3.1 Name ONE property of steel that is tested by conducting a bending test on steel. 3.2 Give TWO reasons for conducting EACH of the following heat-treatment proces... show full transcript
Worked Solution & Example Answer:3.1 Name ONE property of steel that is tested by conducting a bending test on steel - NSC Mechanical Technology Automotive - Question 3 - 2018 - Paper 1
Step 1
Name ONE property of steel that is tested by conducting a bending test on steel.
Answer
One property of steel that can be tested through a bending test is its ductility. Ductility measures the ability of steel to deform under tensile stress, which is crucial when the material is subjected to bending forces.
Step 2
Give TWO reasons for conducting EACH of the following heat-treatment processes on steel: 3.2.1 Annealing
Answer
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To relieve internal stresses in the steel, which can help prevent warping or cracking during further processing.
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To soften the steel, making it easier to work with and shape into desired forms.
Step 3
Give TWO reasons for conducting EACH of the following heat-treatment processes on steel: 3.2.2 Case hardening
Answer
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To produce a wear resistant surface, which extends the lifespan of steel components that face friction and wear.
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To ensure the core remains tough enough to withstand applied loads while maintaining a hard outer layer.
Step 4
Explain why the tempering of steel is done after the hardening process.
Answer
Tempering of steel is done after the hardening process primarily to reduce the brittleness that often results from hardening. This process helps relieve internal strains and can significantly increase the toughness of the steel, making it less prone to fracture.
Step 5
State the THREE factors that must be considered during all heat-treatment processes.
Answer
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Heating temperature / Carbon content: The heating temperature must be controlled based on the carbon content of the steel to achieve the desired microstructure.
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Soaking time: The duration for which the steel is held at a specific temperature can affect the effectiveness of the heat treatment.
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Cooling rate: The speed at which the steel is cooled post-heating is critical in determining its final properties.
Step 6
Explain the hardening process of steel.
Answer
The hardening process involves heating steel to a temperature between 30 to 50°C above its critical temperature, known as the Austenitic range. After achieving this temperature, the steel is maintained for a sufficient time and then rapidly cooled by quenching in water, brine, or oil. This rapid cooling transforms the microstructure of the steel, increasing its hardness.