Heat Treatment Technology Mid - I, September - 2014

1.Homogenization of hyper eutectoid steel for normalizing is done
  • Above A3 temperature
  • Above A1 temperature
  • Above Acm temperature
  • Below A1 temperature
Answer: C
2.Austenitization of steel is not allowed for
  • Stress-relief annealing
  • Full annealing
  • Normalizing
  • Hardening
Answer: A
3.The optimum microstructures for machining of 0.3 to 0.5%C steels can be obtained by
  • Normalising
  • Annealing
  • Water hardening
  • Oil hardening
Answer: B
4.The product of diffusionless transformation is
  • Martensite
  • Pearlite
  • Bainite
  • Austenite
Answer: A
5.The changes in the I-T diagram due to alloying additions to the plain carbon steel does not include
  • Change in shape of the curves
  • Position in the curves
  • Products formed on transformation by different cooling rates
  • Austenization temperature
Answer: D
6.In the mechanism of heat removal during quenching the first stage is called
  • Vapor-blanket cooling state
  • Vapor-transport cooling stage
  • Liquid cooling stage
  • Critical cooling stage
Answer: A
7.The temperature range of bainite formation in steels is
  • Below 4000F
  • 900 to 12000F
  • 1000 to 15000F
  • Above lower critical temperature
Answer: B
8.Most efficient method of increasing the hardenability of the steel is
  • Increasing the cooling rate
  • Increasing the carbon content
  • Increasing the heating time
  • Adding alloying elements
Answer: D
9.Protective atmospheres are required for
  • Bright annealing
  • Surface hardening
  • Full hardening
  • Carbonitriding
Answer: A
10.Rate of heating is maximum in
  • Muffle furnace
  • Pit furnace
  • Conveyor furnace
  • Salt bath furnace
Answer: D
11.Pearlite transformation in steels is ------------------------ phenomenon.
Answer: Diffusion controlled
12.Softening of cold worked steel by process annealing occurs by the mechanism of -------------.
Answer: Recrystallization
13.The hardness of pearlite phase is ----------------.
Answer: 40
14.Martensite in mild steel is obtained by ---------------------.
Answer: Site cannot be formed /produced
15.The properties of the heat treated product would depend on ----------------------.
Answer: The base material as well as the products formed on heat treatment
16.The Ms temperature for eutectoid steel is about --------------- 0F.
Answer: 4000F
17.The ductility and toughness of the steel is increased by --------------.
Answer: Hardening followed by tempering
18.The dew point of cracked ammonia is ---------------.
Answer: -15 - -400C
19.Endothermic atmospheres are produced by burning town gas with -----------.
Answer: Air in presence of nickel
20.…………... is used as a measure of carbon potential for endothermic gases in heat treatment furnaces.
Answer: CO2