The ductility of a material with work hardening
In the case of rubber, vulcanization refers to the process of producing a
Ans. (c) An elastomer is produced by heating raw rubber with sulphur. Sulphur forms covalent bonds with the carbon, by saturating the remaining double bond in each monomer.
This reaction, known as vulcanization, produces additional link between chains called cross
From the lists given below, choose the most appropriate set of heat treatmentprocess and the corresponding process characteristics
Which one of the following is true?
Match List I with List II and select the correct answer:
On completion of heat treatment, the resulting structure will have retainedAustenite if
Which of the following fibre materials are used for reinforcement in compositematerials?
2. Boron carbide
Select the correct answer using the codes given below:
During heat treatment of steel, the hardness of various structures in increasing order are
Consider the following statements:
The strength of the fibre reinforced plastic product
1. Depends upon the strength of the fibre alone
2. Depends upon the fibre and plastic
3. Is isotropic
4. Is anisotropic
Which of these statements are correct?
Ans. (d) Fibre Reinforced plastics are composite materials possessing additional and/or superior properties to individual components.
Carburized machine components have high endurance limit becausecarburization
Wood is a natural composite consisting of which of the following?
TTT diagram indicates time and temperature transformation of
Which one of the following materials is not a composite?
Ans. (d) SIALON: Hot pressing and sintering of an appropriate mix of Al2O3 and Si3N4
powders yielded an excellent composite ceramic tool called SIALON which are very hot hard, quite tough and wear resistant. These tools can machine steel and cast irons at high speeds (250 – 300 m/min). But machining of steels by such tools at too high speeds reduces the tool life by rapid diffusion.
The iron-carbon diagram and the TTT curves are determined under
Nano composite materials are highly preferable in design consideration for their
Consider the following treatments:
4. Cold working
Hardness and tensile strength in austenitic stainless steel can be increased by
Ans. (d) Hardness and tensile strength in austenitic steel can be increased by cold working alone.
Which of the following composites are 'dispersion-strengthened composites’?
1. Particulate composites consist of discrete particles of one material surrounded by a
matrix of another material.
2. Dispersion-strengthened materials are particulate composites where a small amount of hard, brittle, small particles (typically, oxides or carbides) are dispersed through-out a softer, more ductile matrix.
Quenching in not necessary when hardening is done by
Two plain carbon steel specimens having 0·8% carbon content are welded. If weobserve the weldment under Metallurgical Microscope from centre towards eitherside, the following structures are observed at different zones:
1. Fine Pearlite
2. Coarse Pearlite
Select the correct sequence using the codes given below:
Maximum cooling rate produces Martensite
Medium cooling rate produces Fine pearlite
Low cooling rate produces coarse pearlite.
If the surface of a component is heavily stressed while the stresses in the core areof comparative small magnitude, which one of the following heat treatment methods is employed?
Ans. (c) case carburizing if they do not respond to quenching process.