Name and describe the FOUR tests used to distinguish between the different types of materials - NSC Mechanical Technology Automotive - Question 3 - 2019 - Paper 1
Question 3
Name and describe the FOUR tests used to distinguish between the different types of materials.
Give the reason why the following heat-treatment processes are perfor... show full transcript
Worked Solution & Example Answer:Name and describe the FOUR tests used to distinguish between the different types of materials - NSC Mechanical Technology Automotive - Question 3 - 2019 - Paper 1
Step 1
Tests to distinguish between different types of materials
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Bending Test: This test involves hitting the material with a hammer to assess its rigidity and ductility. A material that bends easily without breaking is considered more ductile.
Filing Test: By using a file on the material, one can evaluate its hardness and ease of machining. Softer materials will be easier to file than harder counterparts.
Machining Test: This involves using a machine tool to shave off material. It helps to identify the machinability of different materials based on the ease of cutting and the quality of the surface finish.
Sound Test: Dropping the material on a hard surface can produce sounds that indicate the material properties, such as density and brittleness. High-frequency sounds typically indicate a denser material.
Spark Test: This test involves observing the shape and color of sparks produced when a material is ground. Each type of metal produces a characteristic spark pattern that can help differentiate between them.
Step 2
3.2.1 Tempering
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Tempering is performed on hardened steel to relieve the strains induced during the hardening process. This helps to reduce brittleness, ensuring that the steel attains a balance of toughness and hardness.
Step 3
3.2.2 Normalising
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Normalising is a heat treatment process used to relieve the internal stresses within the steel, resulting in improved mechanical properties and uniformity in structure.
Step 4
3.2.3 Hardening
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Hardening is aimed at producing extremely hard steel which enables the material to resist wear and tear during use. This process increases the hardness by changing the microstructure of the steel.