oan Taking into account the heterogeneity of the specimen it cannot be
ERAT said with certainty that in the as-forged condition there was an
Ss increase in the austenite content (+0.36%) after ageing, as no
ln, statistical study was done through several determinations of the
E austenite content before nor after ageing.
a Austenite content found by the metallographic method was very close
tag to that determined by X-ray diffractometry. However, as only the
white regions resolved with 200x magnification were counted, the
result 0.99% is underestimated. Thus, the volumetric fraction of
le "white constituents" should be higher than the volumetric fraction
TEs determined through X-ray diffractometry. This reinforces the
), 38 shown suspicion that the "white constituents" are not only austenite.
The results of the microsegregation degree evaluation of nickel,
a molybdenum and titanium by the electron microprobe are condensed in
LL Table II.
CL __ ___ Homogenization time at 1197°5 Th) 1
0 0 (As-forged)l 1.5 | 10 | 25 | 35 | s0
_ Ni 7960 8210 8120 8190 8220 8232 1
Dan I | Mo 254
Hm Ti 91.5 94.7 88.6 94.1 | 86.2 89.0
| Ni 270 1 221 17.8 101 95 82
S 27.2 22.1 8.6 7.0
Ti | 19.4 17.4 | 8.2 | 4.9 39 4.2
oy LN 3.4 1.2 1.0
(%) 10.9 2.8
Ti 21.2 18.4 9.2 4.8 4,5 4.7
oo _ Ni | 8496 8554 8458 8451 8454 8397
able 1, I 17 Mo 307 273
sy "TH 137 79
Ni | 6689 7045 7573 7916 7956 8039
I 233 |
f the " TTI 56 I 6 85 | 76 | 80 _
Ni 1.27 1.07 1.04
[14/1 1.57 1.50
FREE 2.45 2.08 1.54 1.24 1.27 1.24
I=average of 100 X-ray intensities, S=standard deviation of a sample,
CV=coefficient of variation, Iy~maximum value of X-ray intensity, I =minimum
value of X-ray intensity, I/1 =quotient that reflects the segregation ratio
TABLE II - Electron microprobe results.
The results of Iw In and CV for the as-forged condition show that the
most segregated element is titanium followed by molybdenum and nickel,
a in accordance with Reference 8. The diagrams shown in Figures 13, 14
and 15 show the segregation profilesofnickel, molybdenum and titanium
Prakt. Met. Sonderbd. 21 (1990)
147