Mechanical Engineering - Engineering Materials - Discussion
Discussion Forum : Engineering Materials - Section 2 (Q.No. 2)
2.
The hardness of steel depends upon the
Discussion:
32 comments Page 2 of 4.
Shivaprasad said:
7 years ago
Amount of cementite it contains imparts of hardness. I think correct answer is A.
Mech said:
7 years ago
(b) is the correct answer because in question steel is give and for steel it is carbon. But for cast iron cementite is used.
Santosha said:
7 years ago
I think it depends on shape and distribution of carbides in iron.
J gani said:
7 years ago
Carbon up to 0.6% it will increase the hardness, then it depends upon cemented content in the metal, answer is cementite.
Gaurav said:
8 years ago
Amount of carbon can't decide hardness of steel because if it is in free form (graphite) it will impart softness.
Zeeshan said:
8 years ago
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.
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.
Sathia said:
8 years ago
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.
Amarjeet Kumar mehra said:
8 years ago
I think it is the amount of cementite.
Ankitha said:
8 years ago
I think the amount of cementite defines hardness.
Farhan Malik said:
8 years ago
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.
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.
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