__________ of austenite decreases the hardenability in steel.
Fine grains
Coarse grains
Homogeneity
Dissolved elements (except cobalt)
Correct Answer :
D. Dissolved elements (except cobalt)
Related Questions
Which of the following parameters is not responsible for the heat loss from a hot steam carrying bare pipe surface located in a room without fans?
Emissivity of pipe surface
Diameter & length of the pipe
Temperature of hot pipe surface & that of air in the room
None of these
'Ice point' is designated on Fahrenheit temperature scale by
0°
32°
62°
212°
Hydrogen in liquid steels is dissolved
As tiny gas bubbles
In the atomic form
In the ionic form
In the molecular form
Force between the molecules of the same substance is called __________ force.
Adhesive
Cohesive
Molecular
Vander Walls
Pick out the correct statement about the condensation.
Filmwise condensation gives a lower heat transfer rate than the dropwise condensation
Suitable coating or vapour additive is used to promote film wise condensation
If a condensing liquid does not wet the surface dropwise, even then condensation will take place on it
Reynolds number of condensing liquid is based on its mass flow rate
Primary designation of steel is based on its
Hardness & tensile strength
Carbon content
Iron content
Alloying elements content
__________ is the hardest oxide and is hence used where high wear resistance at high temperature is required.
Beryllium
Zirconia
Alumina
Magnesia
While the thermosetting polymers are amorphous in nature, the thermoplastic polymers are either amorphous or crystalline. The crystalline polymers are characterised by the
Low impact strength
High flexibility
Better finish and surface appearance
High plastic deformation
Ammonia leakage in the refrigeration system is detected by
Sulphur stick, which on detection gives white smoke
Using chemical reagents
Its smell
Soap solution
Which of the following materials has the maximum shrinkage allowance?
Brass
Cast iron
Lead
Aluminium alloy
The most suitable material of construction for a sewer to carry sewage under high pressure is
Asbestos cement
Steel
Cement concrete
Stoneware
Which of the following is resistant to the action of both heat & chemicals?
Borosilicate glass
Silica glass
Soda lime glass
None of these
Nusselt number is related to Grashoff number (Gr) in turbulent & laminar flow respectively, in respect of free convection over a vertical flat plate as
Gr0.25, Gr
Gr0.25, Gr0.33
Gr, Gr0.25
Gr0.33, Gr0.25
Faraday's law of electrolysis is related to the
Cation speed
Atomic number of the cation
Equivalent mass of the electrolyte
None of these
An ideal material for making cooking vessels should have
High heat capacity
Low heat capacity
High thermal conductivity
Both (B) and (C)
Factor of safety in machine design is defined as the ratio of ultimate stress to __________ stress.
Working
Bearing
Yield
None of these
Exposure to __________ accelerates the degradation of plastics.
Ultraviolet radiation
High atmospheric temperature
High ambient temperature
Damp atmosphere
The minimum temperature to which the water can be cooled in a cooling tower is the __________ temperature of air.
Ambient
Dry bulb
Dew point
Wet bulb
Which of the following is not the commercial name of poly-methyl-methacrylate (PMMA)?
Styrofoam
Lucite
Perspex
Plexiglass
Co-efficient of performance of a Carnot cycle refrigerator operating between - 23°C and + 27°C is
3
5
0.5
1.5
Materials having resistivity ranging from 1 to 100 ohm. cm is termed as
Conductor
Insulator
Semi-conductor
None of these
The only suitable method for hardening the low carbon steel is case hardening. Which of the following is a case hardening process?
Cyaniding
Sherardizing
Spheroidising
None of these
Depreciation of machines fails under the indirect expenses head. As per income tax regulations, it is calculated by the __________ method.
Diminishing balance
Sinking fund
Multiple straight line
Sum of the years digit
Melting point & boiling points of liquid oxygen are respectively - 218.8°C & - 183°C, while the same for liquid nitrogen is - 210°C & - 195.8°C respectively. The difference in melting points of liquid oxygen & liquid nitrogen is not equal to 8.8
°C
°F
°K
°R
Angular displacement can be measured suitably by a
Shaft encoder
Linear variable differential transducer (LVDT)
Stroboscope
Tachometer
The softness or hardness of a grinding wheel depends upon the type & amount of bonding material used. For general purpose cutter grinding __________ grinding wheel is normally used.
Hard
Soft
Silicon carbide
Aluminium oxide
Which of the following is used to produce draught in the locomotive boilers?
Chimney
Induced draught fan
Forced draught fan
Steam jet arrangement
Heat required to raise the temperature of a body by 1 °C is called its
Heat capacity
Specific heat capacity
Thermal conductivity
Water equivalent
Principal alloying elements of cast tool alloys which have very high wear resistance & high temperature strength are
Cobalt, chromium & tungsten
Cobalt, chromium & nickel
Molybdenum, tungsten & chromium
Cobalt, zirconium & molybdenum
Which one can be directly solidified from gaseous state without entering into liquid state?
Helium
Oxygen
Carbon dioxide
None of these