Question

Machinability of hard alloys and tool steels is improved by:

• A. Annealing
• B. Normalising
• C. Spheroidising
• D. Tempering

Hint:

Annealing softens hard steels, making them easier to cut or machine — ideal for improving machinability.

Answer 1

The Correct Option is A

Step 1: What is Machinability?
Machinability refers to how easily a material can be cut, shaped, or removed using a cutting tool. Step 2: Role of Annealing
- Annealing is a heat treatment process that softens the material. - It involves heating the metal to a specific temperature and then cooling it slowly. - This process reduces hardness, refines grain structure, and relieves internal stresses. - As a result, the material becomes less resistant to cutting, hence more machinable. Step 3: Other Options
- Normalising: Increases toughness and strength but doesn't soften the metal significantly. - Spheroidising: Mainly used in carbon steels to form globular cementite, improving ductility, but not directly aimed at hard alloys or tool steels. - Tempering: Used to reduce brittleness in quenched steels, but not primarily for improving machinability. Conclusion: Annealing is the most suitable method to enhance machinability of hard alloys and tool steels.