1. In full annealing, hypereutectoid steels are furnace cooled from above A3. Wh

ID: 796839 • Letter: 1

Question

1. In full annealing, hypereutectoid steels are furnace cooled from above A3. Why are hypereutectoid steels furnace cooled from above A3,1?

a. so all the carbides are dissolved

b. so a proeutectoid cementite network doesn't reform

c. to transform all the a-ferrite

d. to conserve fuel

e. to transform the pearlite to a-ferrite

2. Hardenability

a. moves the TT diagram to the right

b. reduces the critical cooling rate

c. slows the transformation of y-austenite

d. enables austenite to reach Ms

e. all the above

3. A fully (100%) martensitic structure is accomplished when

a. y-austenite is retained to room temperature

b. bainite is formed

c. carbon content is increased

d. y-austenite is cooled to below the Mf temperature

e. hardenability is increased

4. The Ms temperature is

a. raised by all alloying elements but cobalt

b. where pearlite begins to form

c. raised most significantly by carbon

d. raised by any alloying element

e. lowered most significantly by carbon

5. The hardness of martensite is dependent on

a. the rate of cooling

b. the carbon content of the steel

c. the alloying elements present

d. the number of carbides present

e. the proeutectoid phase present

Explanation / Answer

In full annealing, hypereutectoid steels are furnace cooled from above A3. Why are hypereutectoid steels furnace cooled from above A3,1?