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 the normalising process? 3.4 Identify the type of steel/iron from the spark patterns shown in FIGURES 3.4.1–3.4.3 below. 3.5 FIGURE 3.5 below shows an iron-carbon equilibrium diagram. Label A to D.

NSC Mechanical Technology Welding and Metalwork Heat treatment of steel and effect of temperature: 3.1 Define tempering of steel.

3.1 Define tempering of steel - NSC Mechanical Technology Welding and Metalwork - 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 Welding and Metalwork - 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 to improve the ductility induced during the hardening process. This involves heating the hardened steel to a specific temperature and then cooling it, which enhances its toughness.

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 set up during the working of metal, preventing potential failures.
To soften steel in order to facilitate the machining process, making it easier to work with.
To refine the grain structure, improving the mechanical properties and toughness of the steel.

Step 3

At what approximate temperature is steel heated during the normalising process?

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Answer

Steel is approximately heated above the higher critical temperature, which can be around 800-900°C depending on the alloy composition.

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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Answer

3.4.1 - High-carbon steel

3.4.2 - Low-carbon steel / Mild steel

3.4.3 - Cast iron

Step 5

FIGURE 3.5 to label A to D.

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Answer

A - Temperature range / °C

B - Higher/upper critical temperature line

C - Lower critical temperature line

D - Carbon content / % carbon

3.1 Define tempering of steel - NSC Mechanical Technology Welding and Metalwork - Question 3 - 2022 - Paper 1

Worked Solution & Example Answer:3.1 Define tempering of steel - NSC Mechanical Technology Welding and Metalwork - Question 3 - 2022 - Paper 1

Define tempering of steel.

Give THREE reasons why the annealing process is conducted on steel.

At what approximate temperature is steel heated during the normalising process?

Identify the type of steel/iron from the spark patterns shown in FIGURES 3.4.1–3.4.3 below.

FIGURE 3.5 to label A to D.

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