Mechanical Engineering - Engineering Materials - Discussion


The hardness of steel depends upon the

[A]. amount of cementite it contains
[B]. amount of carbon it contains
[C]. contents of alloying elements
[D]. method of manufacture of steel

Answer: Option B


No answer description available for this question.

Prabhu said: (Mar 10, 2014)  
I think it is amount of carbon content. How you can say opt: A Please explain?

Syam said: (Aug 2, 2014)  
I think by increasing percentage of carbon to increase the hardness of steel.

Venki said: (Dec 2, 2014)  
This answer will be carbon content.

Alok said: (Feb 25, 2015)  
Increase in amount of carbon contain hardness increase.

Kishore Ram said: (Jun 11, 2015)  
If carbon present in combined form then its called cementite and cementite is present then steel is more harder.

Sagar said: (Jun 26, 2015)  
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.

Imran said: (Feb 28, 2016)  
Perhaps amount of cementite present.

Amit Gaikwad said: (Jun 5, 2016)  
Why not with the amount of cementite it contains?

Rabi Marndi said: (Jul 7, 2016)  
As per my knowledge, the correct answer is Amount of cementite it contains.

Vikas said: (Dec 25, 2016)  
I tink the answer is amount of cementite it contains.

Amal said: (Mar 16, 2017)  
I think the amount of cementite.

Prudvi said: (Apr 14, 2017)  
The correct answer is carbon content.

Farhan Malik said: (May 10, 2017)  
Cementite is the main component which imparts hardness.

Steels containing >0.8% Carbon are hard because they contain cementite and pearlite.

Steels containing <0.8% Carbon are soft because they contain ferrite and pearlite.

Ankitha said: (May 12, 2017)  
I think the amount of cementite defines hardness.

Amarjeet Kumar Mehra said: (Jul 18, 2017)  
I think it is the amount of cementite.

Sathia said: (Sep 1, 2017)  
If the question were to ask regarding hardness of iron in general, then the presence of carbon induces propotional hardness, but in this case for steel carbon is in dissolved form (cementite) so, for steel amount of cementite affects the hardness.

Zeeshan said: (Sep 6, 2017)  
I have a practical case to discuss.

A part made from carbon steel become cracked after welding. We have checked the hardness of cracked part and an another part that was not cracked after welding. Hardness was almost same. (92~97 HRB). The only difference between two samples was one that was not cracked when flatten with hammer become flat easily and another one becomes further cracked and split into two pieces during flattening.

Gaurav said: (Nov 7, 2017)  
Amount of carbon can't decide hardness of steel because if it is in free form (graphite) it will impart softness.

J Gani said: (Apr 24, 2018)  
Carbon up to 0.6% it will increase the hardness, then it depends upon cemented content in the metal, answer is cementite.

Santosha said: (Jul 20, 2018)  
I think it depends on shape and distribution of carbides in iron.

Mech said: (Sep 14, 2018)  
(b) is the correct answer because in question steel is give and for steel it is carbon. But for cast iron cementite is used.

Shivaprasad said: (Oct 8, 2018)  
Amount of cementite it contains imparts of hardness. I think correct answer is A.

Reuben George said: (Dec 5, 2018)  
According to me, the hardness of steel depends on carbon content.

Naveen said: (Jan 1, 2019)  
I think the amount of cementite contains is the correct answer.

Sid said: (Feb 16, 2019)  
The correct Answer will be C.

Haie said: (Jun 6, 2019)  
Option C is right.

Darshan S B said: (Aug 14, 2019)  
I think carbon increase hardness of cast iron.

But cementite increase hardness of steel.

Sai said: (Feb 29, 2020)  
In Rs khurmi book also he said the amount of cementite is given. So cementite is right.

G Reddy said: (Apr 17, 2020)  
Carbon increases the hardness of iron.

Cementite increases the hardness of steel.

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