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The table below describes heat treatments which have been applied to each of the medium-carbon steel screwdrivers A and B - Leaving Cert Engineering - Question 3 - 2013
Question 3
The table below describes heat treatments which have been applied to each of the medium-carbon steel screwdrivers A and B. Screwdriver A Heat to 900°C and allow to ... show full transcript
Worked Solution & Example Answer:The table below describes heat treatments which have been applied to each of the medium-carbon steel screwdrivers A and B - Leaving Cert Engineering - Question 3 - 2013
Step 1
Describe the effect of applying maximum torque to both screwdriver A and screwdriver B after the above heat treatments.
Answer
Screwdriver A, having been subjected to annealing, will be softer and more ductile. This makes it more likely to deform under maximum torque, which can lead to permanent bending or warping of the blade. In contrast, screwdriver B, which has been hardened, will exhibit greater brittleness. Therefore, applying maximum torque to screwdriver B may result in cracking or snapping, as it cannot absorb the stress without fracturing.
Step 2
Outline the most effective heat treatment process that should be applied to a screwdriver.
Answer
To enhance the durability and functionality of a screwdriver, it should undergo a quenching process after being heated to a temperature of around 900°C. This should be followed by tempering to relieve stresses and improve toughness. The tempering temperature should range from 200°C to 300°C, allowing the screwdriver to maintain a hardened outer layer while achieving better resistance against impacts, minimizing brittleness.
Step 3
Step 4
Describe in detail, the point X with reference to the following: - phase change - composition - temperature.
Answer
At point X, a phase change occurs indicating the transition from austenite to pearlite as the carbon content is approximately 0.83%. The composition at this point is a balanced mix of ferrite and cementite (Fe3C). The temperature at point X corresponds to the eutectoid temperature, which is approximately 723°C, where the structure is stable and represents the ideal alloy configuration for medium-carbon steel.
Step 5
Describe the process and applications of induction hardening.
Answer
Induction hardening involves using high-frequency alternating current to generate a magnetic field around a component. This magnetic field induces eddy currents which heat the surface of the material rapidly. The high temperature allows the surface to transform into austenite before being quenched in water or oil to harden. This process is commonly applied in components requiring increased surface hardness such as gears, shafts, and high-wear parts.
Step 7
Outline the operating principles of an optical pyrometer.
Answer
An optical pyrometer measures temperature by comparing the brightness of the light emitted by a hot object with that from a standard light source. It uses a calibrated light filter to determine the temperature based on the intensity of the emitted light. The adjustment allows the user to find a temperature reading that corresponds with the hot object's emission. This method is widely used for high-temperature measurements where contact thermometers are impractical.
Step 8
Explain the properties of 18/10 stainless steel and outline a suitable use for this steel.
Answer
18/10 stainless steel consists of 18% chromium and 10% nickel, which confers excellent corrosion resistance and a bright, polished finish. It is non-reactive and easy to clean, making it ideal for culinary applications. A suitable use for this steel is in high-quality cookware, such as pots and pans, which endure significant heat and require durability and resistance to staining.