Briefly describe the phenomena of superheating and supercooling.
Why do these phenomena occur?
Make a copy of the isothermal transformation diagram for a 0.45 wt% C iron-carbon alloy (Figure 10.40), and
then sketch and label on this diagram the time-temperature paths to produce the following microstructures:
42% proeutectoid ferrite and 58% coarse pearlite
50% fine pearlite and 50% bainite
50% martensite and 50% austenite
Briefly explain why the hardness of tempered martensite diminishes with tempering time (at constant temperature)
and with increasing temperature (at constant tempering time).