Correct option is A
Tempering is a heat treatment process used to
increase toughness and reduce brittleness in hardened steel. After steel is hardened by rapid cooling (quenching), it becomes very hard but brittle. To make the steel tougher and more ductile, it is reheated to a temperature below its critical point and then cooled slowly. This process relieves internal stresses and improves its mechanical properties without losing too much hardness.
Process of Tempering:
Steel is heated to temperatures between
150°C and 650°C, depending on the desired toughness.
It is then cooled in air, oil, or water.
Applications: Used in making tools, automotive components, springs, and cutting edges where a balance between hardness and toughness is needed.
Effect of Tempering Temperature:
Low Tempering (150–250°C): Retains high hardness with minimal toughness (used in cutting tools).
Medium Tempering (300–450°C): Increases toughness, suitable for mechanical parts.
High Tempering (500–650°C): Produces highly tough steel for heavy-duty applications like gears and shafts.
