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3. (a) Describe any two of the following heat treatment processes: (i) Hardening, (ii) Annealing, (iii) Tempering - Leaving Cert Engineering - Question 3 - 2011
Question 3
3. (a) Describe any two of the following heat treatment processes: (i) Hardening, (ii) Annealing, (iii) Tempering. (b) (i) Outline one reason for the damag... show full transcript
Worked Solution & Example Answer:3. (a) Describe any two of the following heat treatment processes: (i) Hardening, (ii) Annealing, (iii) Tempering - Leaving Cert Engineering - Question 3 - 2011
Step 1
Describe any two of the following heat treatment processes: (i) Hardening
Answer
Hardening is a process applied to high carbon steel by heating it to a cherry red and then cooling rapidly, often in oil or water. This rapid cooling alters the microstructure of the steel, increasing its hardness significantly. The hardening process transforms the austenitic structure into martensite, which is much harder but also more brittle, making it essential to follow up with proper tempering.
Step 2
Describe any two of the following heat treatment processes: (ii) Annealing
Answer
Annealing is conducted to soften metal and relieve internal stresses. The process involves heating the metal to a red color and allowing it to cool very slowly, typically in a furnace. This slow cooling helps to reduce hardness, improve ductility, and eliminate residual stresses formed during previous processes, thereby preparing the material for further machining or use.
Step 3
Outline one reason for the damage to the point of the centre punch, shown at A.
Answer
One reason for damage to the point of the centre punch is that it has not been properly hardened or tempered, resulting in the tip becoming too soft. If the tool is excessively heated during use, it can lose its hardness, leading to deformation or chipping at the tip, especially when striking harder surfaces.
Step 4
Explain one method to prevent damage to the point of a centre punch.
Answer
To prevent damage to the point of a centre punch, it is crucial to ensure the punch is properly hardened and tempered to the correct level. Regular cooling during grinding operations can also help maintain the integrity of the edge, minimizing the risk of overheating and subsequent damage during use.
Step 5
State two safety precautions to be observed when using water for cooling during heat treatment.
Answer
- Wear protective clothing to protect from hot water splashes or rising steam.
- Perform hardening processes in a well protected area away from busy environments to reduce the risk of accidents due to hot materials or unexpected splashes.