Mechanical Engineering - Engineering Materials - Discussion

I think it is amount of carbon content. How you can say opt: A Please explain?

I think by increasing percentage of carbon to increase the hardness of steel.

This answer will be carbon content.

Increase in amount of carbon contain hardness increase.

If carbon present in combined form then its called cementite and cementite is present then steel is more harder.

Free carbon is the part of the total carbon in steel or cast iron that is present in elemental form as graphite or temper carbon. In steels none of the carbon is present as free carbon; it is all dissolved in the iron.

As free carbon is a major impurity, the pig iron becomes brittle and hard. Pig iron may be made into steel (with up to about 2% carbon) or wrought iron (commercially pure iron) through oxidizing some or all of the carbon, together with other impurities.

The hardness of the steel depends on its carbon content: The higher the percentage of carbon, the greater the hardness and the lesser the malleability. Regardless of the heat treatment, higher carbon content reduces weld ability. In carbon steels, higher carbon content also lowers the melting point.

Perhaps amount of cementite present.

Why not with the amount of cementite it contains?

As per my knowledge, the correct answer is Amount of cementite it contains.

I tink the answer is amount of cementite it contains.