Q. Railway wagon axles are made by heating rods of iron embedded in charcoal powder. The process is known as
A) Case hardening
B) Tempering
C) Sheradizing
D) Annealing
Explanation
(a)
The process of hardening the surface of wrought iron by depositing a surface layer of steel on it is called case-hardening. It is done by heating wrought iron in contact with potassium ferricyanide
Alternatively, case hardening can also be done by heating wrought iron with charcoal and then plunging it in a suitable oil
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.