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3.1 Name ONE property of steel that is tested by conducting a bending test - NSC Mechanical Technology Welding and Metalwork - Question 3 - 2018 - Paper 1
Question 3
3.1 Name ONE property of steel that is tested by conducting a bending test. 3.2 Give TWO reasons for conducting EACH of the following heat-treatment processes on st... show full transcript
Worked Solution & Example Answer:3.1 Name ONE property of steel that is tested by conducting a bending test - NSC Mechanical Technology Welding and Metalwork - Question 3 - 2018 - Paper 1
Step 1
Name ONE property of steel that is tested by conducting a bending test.
Answer
One property of steel that is tested by conducting a bending test is ductility. This property indicates the material's ability to deform under tensile stress, which is crucial for applications that require flexibility and resilience.
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 that may have developed during previous processing, thus enhancing the material's performance.
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To soften the steel, improving its workability for further forming processes.
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 that enhances durability while ensuring that the core remains tough enough to withstand applied loads.
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To create a hard case that provides both surface hardness and increased wear resistance.
Step 4
Explain why the tempering of steel is done after the hardening process.
Answer
Tempering is done after hardening to reduce the brittleness that is typically caused by the hardening process. It also relieves any strains that may have developed during hardening and increases the toughness of the steel, leading to a more reliable and durable material.
Step 5
State the THREE factors that must be considered during all heat-treatment processes.
Answer
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Heating temperature: The temperature to which the steel is heated significantly affects the phase transformations that occur.
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Soaking time: The time the material stays at the heating temperature impacts the uniformity of the heat treatment and the resulting properties.
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Cooling rate: The method of cooling (e.g., air cooling, water quenching) influences the final microstructure and mechanical properties of the steel.
Step 6
Explain the hardening process of steel.
Answer
The hardening process of steel involves heating the material to a temperature range of 30°C to 50°C above its critical temperature (Ac₃) and then rapidly cooling it (quenching). This process transforms the metal's microstructure, increasing its hardness and strength. Once quenched, the steel may require tempering to adjust its properties and reduce brittleness.