Question

5. Using the attached ITT diagram for 1.13 wt% C steel, name the structures present and approximate quantities after the following heat treatments: a) heat to 900°C, quench to 700°C, hold for 10 s, quench to 0°C (the iron-iron carbide phase diagram will help) b) heat to 900°C, quench to 300°C, hold for 1000 s, quench to 0°C c) heat to 900°C, quench to 100°C d) heat to 800°C, quench to 0°C (the iron-iron carbide phase diagram will help)

Answer 1

a)

900 1600 800 Ac 1400 700 1200 600 1000 500 A.B Temperature (°C) 800 400 3 A 300 600 50 200 Mistari 400 N(50%) 100 M199282 200 0 1 10- 10 10* 10 10 The austenite is rapidly cooled to 700 C and held for a constant temperature of 10 seconds, where austenite is transformed into 50% of pearlite and further, remaining austenite is rapidly cooled to 0 C gives the 50%martensite.

b)

900 1600 800 AC 1400 700 AP 1200 600 1000 500 A.B Temperature (°C) 800 400 8 А 300 500 50 200 Mistari 400 100 M(50%) M199281. 200 0 1 10 10 10* 10 10 Tin The austenite is rapidly cooled to 300 C and held for a constant temperature of 1000 seconds, where austenite is transformed into 50% of Bainite and remaining austenite is rapidly cooled to 0 C gives the 50%martensite.

c)

900 1600 800 AC 1400 700 1200 600 1000 500 A.B Temperature (°C) 800 400 B A 300 600 50 200 Mistarti 400 M(50%) 19992. 100 200 0 1 10 10- 10* 10% 10% 10 Times) The austenite is rapidly cooled to 100 C where austenite is transformed into 80% of Martensite rapidly and on further cooling entire composition will be converted into 100% martensite.

d)

900 1600 800 A: 1400 700 A.P. 1200 600 1000 500 A.B Temperature (°C) 200 400 А 300 600 50 200 Mistari 400 M(50% M1998. 100 200 - O 1 10 10- 10 10* 10% 10 The austenite is rapidly cooled to 0 C where austenite is completely transformed into 100% of Martensite