3.1 Define tempering of steel - NSC Mechanical Technology Automotive - Question 3 - 2022 - Paper 1
Question 3
3.1 Define tempering of steel.
3.2 Give THREE reasons why the annealing process is conducted on steel.
3.3 At what approximate temperature is steel heated during t... show full transcript
Worked Solution & Example Answer:3.1 Define tempering of steel - NSC Mechanical Technology Automotive - Question 3 - 2022 - Paper 1
Step 1
Define tempering of steel.
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Answer
Tempering is a process generally applied to steel to relieve the strains, brittleness, and improve ductility that are induced during the hardening process. This helps in enhancing the mechanical properties of the steel, making it more suitable for various applications.
Step 2
Give THREE reasons why the annealing process is conducted on steel.
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Answer
To relieve internal stresses that may have been generated during the working of metal.
To soften steel in order to facilitate the machining process.
To refine the grain structure and reduce brittleness, thus improving ductility.
Step 3
At what approximate temperature is steel heated during the normalising process?
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Answer
Steel is typically heated to a temperature above its higher/upper critical temperature, generally above the A3 line. This allows for structural changes that enhance its mechanical properties.
Step 4
Identify the type of steel/iron from the spark patterns shown in FIGURES 3.4.1–3.4.3 below.
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FIGURE 3.5 below shows an iron-carbon equilibrium diagram. Label A to D.
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Answer
A: Temperature range / °C
B: A3 line / Higher/upper critical temperature line
C: AC1 line / Lower critical temperature line
D: Carbon content / % carbon
