°C
800
700
727°
Coarse pearlite
600
y
a + Fe3C
500
Fine pearlite
400
7+ a + Fe3C
Bainite
300
M
200
M50
M90
100
1 sec
1 min
1 hour
1 day
0
0.1
1
10
102
103
104
105
Time, seconds
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a) Starting at 800 ÂșC, i) quench to 600 ÂșC, hold for 4 seconds, ii) quench to 275 ÂșC, hold for 1000
seconds, iii) quench to room temperature, iv) heat to 500 ÂșC for 1 hour, then cool to room temperature.
i)
ii)
iii)
iv)
b) Starting at 775 ÂșC, i) quench to 640 ÂșC, hold for 10 seconds, ii) quench to 375 ÂșC, hold for 100
seconds iii) quench to room temperature, iv) heat to 350 ÂșC for 2 hours.
i)
ii)
iii)
iv)
