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3.1 Name and describe the FOUR tests used to distinguish between the different types of materials - NSC Mechanical Technology Welding and Metalwork - Question 3 - 2019 - Paper 1
Question 3
3.1 Name and describe the FOUR tests used to distinguish between the different types of materials. 3.2 Give the reason why the following heat-treatment processes ar... show full transcript
Worked Solution & Example Answer:3.1 Name and describe the FOUR tests used to distinguish between the different types of materials - NSC Mechanical Technology Welding and Metalwork - Question 3 - 2019 - Paper 1
Step 1
Name and describe the FOUR tests used to distinguish between the different types of materials.
Answer
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Bending Test: This involves hitting the metal with a hammer to assess its ductility and strength. A more ductile metal will bend without breaking, while a brittle one may shatter.
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Filing Test: In this test, a file is used on the material. The ease with which the file removes material can indicate the hardness of the metal. The colour and ease of filing can also provide insights into the type of material.
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Machining Test: This test uses a machine tool to reshape the material. Observing the type of shavings produced, as well as their ease and colour, helps in identifying the material type.
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Sound Test: A sound is created by dropping the material on the floor. The frequency and quality of the sound (high or low) can signify differences in material density and internal structure.
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Spark Test: A spark is produced when the material is ground against a grinding wheel. By observing the shape and colour of the sparks, one can help classify the metal.
Step 2
Give the reason why the following heat-treatment processes are performed on steel:
Answer
3.2.1 Tempering: This process is performed after hardening to relieve any strains induced in the steel due to quenching. It helps restore some ductility while reducing brittleness, making the material more usable.
3.2.2 Normalising: Normalising is done to relieve internal stresses that remain in steel after fabrication processes. This treatment ensures a more uniform microstructure and improves mechanical properties.
3.2.3 Hardening: The main purpose of hardening is to produce extremely hard steel. This process improves the wear resistance of the steel, allowing it to withstand high levels of abrasion and prolonging its lifespan.