callister7e_sm_ch09_64

Prévia do material em texto

9-76 
 9.64 This problem asks that we determine the approximate Brinell hardness of a 99.75 wt% Fe-0.25 wt% 
C alloy, using a relationship similar to Equation 9.24. First, we compute the mass fractions of pearlite and 
proeutectoid ferrite using Equations 9.20 and 9.21, as 
 
 
Wp =
C 0
' − 0.022
0.74
= 0.25 − 0.022
0.74
= 0.308 
 
 
Wα' =
0.76 − C 0
'
0.74
= 0.76 − 0.25
0.74
= 0.689 
 
Now, we compute the Brinell hardness of the alloy using a modified form of Equation 9.24 as 
 
 
HBalloy = HBα'Wα' + HBpWp 
 
= (80)(0.689) + (280)(0.308) = 141 
Excerpts from this work may be reproduced by instructors for distribution on a not-for-profit basis for testing or instructional purposes only to 
students enrolled in courses for which the textbook has been adopted. Any other reproduction or translation of this work beyond that permitted 
by Sections 107 or 108 of the 1976 United States Copyright Act without the permission of the copyright owner is unlawful.