4.1 Define the term higher critical temperature in the heating of steel - NSC Mechanical Technology Fitting and Machining - Question 4 - 2018 - Paper 1
Question 4
4.1 Define the term higher critical temperature in the heating of steel.
4.2 FIGURE 4.2 below shows a diagram. Answer the questions that follow.
4.2.1 Identify the... show full transcript
Worked Solution & Example Answer:4.1 Define the term higher critical temperature in the heating of steel - NSC Mechanical Technology Fitting and Machining - Question 4 - 2018 - Paper 1
Step 1
Define the term higher critical temperature in the heating of steel.
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Answer
The higher critical temperature is defined as the maximum temperature to which steel can be heated to achieve its greatest hardness. At this temperature, the steel undergoes a transformation that enhances its mechanical properties.
Step 2
Identify the diagram shown in FIGURE 4.2 above.
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Answer
The diagram shown in FIGURE 4.2 is the Iron-carbon phase diagram.
Step 3
Label structures A to G.
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Answer
A - Ferrite + Pearlite
B - Ferrite
C - Ferrite + Austenite
D - Austenite
E - Austensite + Cementite
F - Pearlite + Cementite
G - 100% Pearlite
Step 4
To what temperature should steel, with a carbon content of 1.2%, be heated for hardening?
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Answer
Steel with a carbon content of 1.2% should be heated to approximately 900 °C or between 900 °C and 920 °C for hardening.
