Heat
treatment of steel ________ .
is
effective when the carbon percentage is lower than 0.8%.
can
be used to change the carbon percentage.
involves
heating steel to a temperature above melting point and then cooling.
cannot
be used to relieve local stresses and strains.
involves
heating steel to a temperature above melting point and then cooling.
Heat
treatment of steels involves hearting steel to a temperature above melting
point and then cooling to change their physical and mechanical properties,
without any change dimensions.
Hence,
the correct option is (C).
&Key Points:-
Different heat treatment process of steel are:
Annealing : Heating below recrystallization temperature and then slowly cooling steel to refine it and make it softer.
Carburizing : Adding carbon to the surface with heat and carbon rich substances.
Tempering : Reheating steel that has already been cooled to a specific temperature to remove hardness.
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