A)Starting with a sample of a fine pearlitic steel, describe the most efficient

Question

A)Starting with a sample of a fine pearlitic steel, describe the most efficient way to form a coarse pearlitic steel.

B) Now, with this sample of a coarse pearlitic steel, describe the most efficient way to form a tempered martensitic steel.

C) Now with this sample of a tempered martensitic steel, describe the most efficient way to form a spheroiditic steel.

D) Now with this sample of a spheroiditic steel, describe the most efficient way to return to a fine pearlitic steel (i.e. the steel that you originally started with)

E) What additives to the steel would make it easier to form martensite?

F)In what form should these additives be in so that they are effective?

G) Which one of these steels above would you probably use to make a high quality hand tool and why?

H) Which one of the steels above would you probably use for a low strength application that required a large amount of plastic deformation of the component during manufacture ?

Explanation / Answer

Ans No-(A) as we know Pearlite is formed during sufficiently slow cooling ?in an iron-carbon system at the eutectoid point in the Fe-C phase diagram (723 °C, eutectoid temperature?). whereas

Pearlite for which the alternating ferrite and cementite layers are relatively thick called  coarse pearlitic steel fine pearlitic steel <----->coarse pearlitic steel through  (isothermalheat transfer/marquenching transformation at temperature around 680 0C).

Ans No-(B) martensite, a very hard microstructure formed when coarse pearlitic steel is quenched. Tempering reduces the hardness in the martensite by transforming it into various forms of tempered martensite.

coarse pearlitic steel <----->tempered martensitic steel (through quenching process)

Ans no-(C)  Spheroidite forms when tempered martensitic steel is heated to approximately 700 °C for over 30 hours. Spheroidite can form at lower temperatures but the time needed drastically increases, as this is a diffusion-controlled process.

Ans No-(D)spheroiditic steel can be converted to a fine pearlitic steel through Full annealing process.

Ans no-(E) Tungsten is the additives to the steel would make it easier to form martensite.

Ans no-(G) fine pearlitic steel

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