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Explain any one of the following heat treatment processes: (i) Annealing - Leaving Cert Engineering - Question a - 2007
Question a
Explain any one of the following heat treatment processes: (i) Annealing. (ii) Case hardening. (b) Describe how the point of the scriber shown is hardened and tempe... show full transcript
Worked Solution & Example Answer:Explain any one of the following heat treatment processes: (i) Annealing - Leaving Cert Engineering - Question a - 2007
Step 1
Explain any one of the following heat treatment processes: (i) Annealing.
Answer
Annealing is a heat treatment process primarily aimed at softening metal and relieving internal stresses. The procedure involves heating the metal to a specific temperature that is appropriate for the material properties. After it reaches the target temperature, the metal is allowed to cool down at a controlled rate, which is typically slow. This controlled cooling process minimizes the formation of unwanted structures within the metal, ultimately enhancing its ductility and toughness.
Step 2
Describe how the point of the scriber shown is hardened and tempered.
Answer
The hardening process of the scriber point begins with cleaning and polishing the tip using emery cloth. Once cleansed, the point is then heated until it reaches a cherry red color, often referred to as red heat. Following this, the heated point is rapidly cooled in a process known as quenching, which may involve submerging it in water or oil. This rapid cooling increases the hardness of the metal, transforming it into a very hard but brittle state.
To temper the scriber, the next step is to heat the point to a predetermined temperature, which is critical for improving toughness while retaining some hardness. Typically, this involves reheating the point to just below the red heat, depending on the desired properties, and then allowing it to cool down slowly, either in air or by submerging it once again. This tempering process reduces brittleness and achieves a balance between hardness and toughness, making the scriber functional for its intended purposes.