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Explain how you will conduct the following tests to identify various metals: 3.1.1 Sound test: 3.1.2 File test: What is the purpose of the heat treatment of steel? What is the purpose of the case hardening of steel? Describe the tempering process of steel - NSC Mechanical Technology Fitting and Machining - Question 3 - 2020 - Paper 1
Question 3
Explain how you will conduct the following tests to identify various metals: 3.1.1 Sound test: 3.1.2 File test: What is the purpose of the heat treatment of steel... show full transcript
Worked Solution & Example Answer:Explain how you will conduct the following tests to identify various metals: 3.1.1 Sound test: 3.1.2 File test: What is the purpose of the heat treatment of steel? What is the purpose of the case hardening of steel? Describe the tempering process of steel - NSC Mechanical Technology Fitting and Machining - Question 3 - 2020 - Paper 1
Step 1
3.1.1 Sound test:
Answer
To conduct a sound test for identifying various metals, you would tap the metal with a hammer or similar object. After tapping, listen carefully to the sound produced:
- A high-pitched ringing sound typically indicates a harder, denser metal like steel.
- A dull thud may suggest a softer metal.
Additionally, dropping the metal on a hard surface can provide similar insights based on the quality of the sound produced.
Step 2
3.1.2 File test:
Answer
For the file test, take a file and apply it to the surface of the metal. The result will help you determine the metal's hardness:
- If the file bites deeply into the metal, it indicates that the metal is softer.
- Conversely, if the file hardly bites and glides over the surface, this suggests that the metal is harder.
Step 3
What is the purpose of the heat treatment of steel?
Answer
The primary purpose of heat treatment of steel is to alter its properties.
This process can enhance the strength, hardness, and ductility of steel, making it more suitable for various applications in engineering and construction. Heat treatment can also influence the grain structure, affecting the overall performance of the material.
Step 4
What is the purpose of the case hardening of steel?
Answer
The purpose of case hardening is to create a wear-resistant surface on steel items while maintaining a tough core. This technique improves durability by providing a harder surface that can endure wear and stress, which is particularly beneficial for components subjected to friction.
Step 5
Describe the tempering process of steel.
Answer
The tempering process is performed after steel has been hardened. It involves the following steps:
- Heating: The steel is heated to a specific temperature, typically below its critical temperature.
- Soaking: It is then held at that temperature for a designated period to ensure uniform heating.
- Quenching: After soaking, the steel is rapidly cooled using water, oil, or another quenching medium, which helps to lock in the tempered properties.
Step 6
Name the THREE factors which need to be taken into consideration when heat treatment of steel is done.
Answer
The three key factors to consider when conducting heat treatment of steel are:
- Heating temperature: The specific temperature to which the steel should be heated is crucial for achieving the desired properties.
- Soaking time: The period the steel is held at the target temperature impacts its properties, as insufficient time may not allow full transformation.
- Cooling rate: The speed at which the steel is cooled after heat treatment, which can be measured by the quenching rate, affects hardness and structural integrity.