Steels_ Metallurgy and Applications, Third Edition

54 Steels: Metallurgy and Applications

,~-240

"•220

200

,~. 46

r

0

44

m 42

40

60

~ 5C

e.-

"$ 30

~176176 ~

oo -~

"', 9 550~

300~ , A 600~

Overageing ,~ 650oc

temperature Quenching temperature

'b'=~,= b b

9 A

Coolin.q rate (~

Figure 1.57 Effect of cooling rate and overageing temperature on the mechanical prop-
erties of an aluminium-killed steel annealed at 800"C (After Obara et al. 91)

60

A r

Q.

X |

'10

.-r 40

.=., r

|

20

250~

9 ~. r 9 ..... 9 450 ~

""&~~ "s ~--- 400 ~

~

""~-..A.. % - 9 350 ~

300o13

100 1000

Time (s)

Figure 1.58 Variation of ageing index with time for aluminium-killed steel for different
overageing temperatures after isothermal overageing (After Katoh et al. 92)