Protective gas used in the annealing furnace for steel coil comprises of__________________?
(A) 95% N2 + 5% H2
(B) 5% H2 + 9% N2
(C) 100% CO
(D) 100% H2
Artificial draught produced by a fan in the furnace can be controlled by the___________________?
(A) Speed of the fan
(B) Damper
(C) Variation in the pitch of fan blades
(D) All
Which of the following is the most suitable for preheating combustion air above 650°C ?
(A) Regenerator
(B) Metallic recuperator
(C) Ceramic recuperator
(D) None of these
The electric furnace in which heat is produced by a combination of induced current and skin effect is called _____________ furnace?
(A) Arc
(B) Resistance
(C) Low frequency induction
(D) High frequency induction
Thermal efficiency of an open hearth furnace may be about _____________ percent?
(A) 5
(B) 20
(C) 50
(D) 80
While the fuel fired furnace can be used upto a maximum temperature of about 1700°C, the electric furnace can be used upto a temperature of about _____________ °C?
(A) 2000
(B) 3000
(C) 4500
(D) 6000
Power required in case of forced draught as compared to induced draught (for the same draught produced) is___________________?
(A) Same
(B) Less
(C) More
(D) Either more or less; depends on the flue gas density
Thermal efficiency of furnaces can be improved by____________________?
(A) Waste heat recovery from flue gas
(B) Minimising heat losses from furnace walls
(C) Maintaining proper draught
(D) All
Pick out the correct statement?
(A) Stainless steel is nothing but chromium coated steel
(B) Hardening of a soft metal can be done by alloying it with another metal or non-metal
(C) Plastic deformation of a material is its temporary distortion under the action of applied stress
(D) Rusting of iron is not electrochemical in nature
Pick out the wrong statemen?
(A) Hardening makes the steel more brittle
(B) High alloy steels contain more than 50% alloying element
(C) 18/8 stainless steel is a magnetic steel
(D) Both