4.1 State TWO properties of the cementite structure of carbon steel - NSC Mechanical Technology Welding and Metalwork - Question 4 - 2016 - Paper 1
Question 4
4.1 State TWO properties of the cementite structure of carbon steel.
4.2 What is the purpose of case hardening on a camshaft?
4.3 What is the purpose of tempering ... show full transcript
Worked Solution & Example Answer:4.1 State TWO properties of the cementite structure of carbon steel - NSC Mechanical Technology Welding and Metalwork - Question 4 - 2016 - Paper 1
Step 1
State TWO properties of the cementite structure of carbon steel.
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Answer
Cementite, also known as iron carbide (Fe₃C), has the following properties:
It is hard, contributing to the overall hardness and wear resistance of steel.
It is brittle, making it susceptible to cracking under stress.
Step 2
What is the purpose of case hardening on a camshaft?
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Answer
The purpose of case hardening on a camshaft is twofold:
To ensure hardness on the surface, providing wear resistance during operation.
To ensure a soft and tough interior (core) which provides resilience and prevents fracture.
Step 3
What is the purpose of tempering hardened steel?
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Answer
Tempering hardened steel serves to reduce brittleness, making it less likely to fracture during use. Additionally, it helps to increase toughness, thereby improving the material's overall performance.
Step 4
Show, by means of a neat drawing, the following elements on an iron-carbon equilibrium diagram:
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Answer
The drawing should depict the iron-carbon equilibrium diagram with the following elements:
Carbon content from 0% to 1.4%: This is the x-axis range, indicating the percentage of carbon.
Temperature of 0 °C to 1 000 °C: This is the y-axis range, showing the temperature in degrees Celsius.
AC1-line: Indicated on the diagram showing the transformation points.
AC3-line: Similarly indicated on the diagram.
Austenite structure: Represented in the diagram at the appropriate temperature and carbon content.
Ferrite structure: Shown where the carbon content is below 0.76% in the diagram.
Pearlite structure: Located in the region between the ferrite and cementite in the diagram.
