Question

Annealing of steel is the process of heating steel:
(a)to a bright red hot and then cooling it slowly
(b)to a bright red hot and then cooling it suddenly
(c)to a temperature much below redness and cooling it slowly
(d)none of the above

Answer 1

Annealing is a heat treatment which changes the physical properties and some chemical properties of materials to soften it or increase its ductility. This would make the material in a workable shape.
Complete step by step solution : Annealing is a process in which steel is heated and then cooled. It softens the steel. For steel it is cooled slowly at a controlled rate. Annealing in steel restores ductility.

Hence, the correct answer to the question is option (a).

Additional Information:
-Annealing is mainly used to soften steel, improve its machinability and increase its conductivity. In cold working, the metals become so hard that, if any more work is applied it will cause cracks in the metal.
-This method is mainly used for steel. Annealing steel is done in large ovens. The oven is large enough for the air to circulate through the entire metal. Gas conveyor furnaces are used for large pieces, while for small pieces of steel car-bottom furnaces are used.
-In the process, steel is heated to a particular temperature at which it re-crystallises. At this stage, if any defects are present, it is repaired. For a fixed amount of time, it is kept at this temperature, and then it is allowed to cool to room temperature.
-It is then cooled very slowly so that it could form refined microstructures, which increases softness. Cooling is done by simply switching off the furnace and with the hot metal piece. It gradually comes to room temperature.

Note : In the process of annealing, the steel is first heated to high temperature, and then it is cooled slowly to room temperature. It is not cooled rapidly.