40 Prakt. Met. Sonderband 38 (2006) 
higher annealing temperatures would result in more recrystallized ferrite, not less. However, since the steels 
driving force for austenite formation is much higher than for the recrystallization of ferrite, the higher 
formation of the austenite would take preference and would be especially noticeable in the specimen 
annealed at 860°C. Also, nearly 4% retained austenite was found at 450°C, in the absence of isothermal Ackn 
holding at 450°C, in the samples annealed at 770°C. This is no doubt related to the initially higher 
carbon content of the initial austenite formed at 770°C. The 
Mater 
0.1 spons 
0.1 * Refer 
0. 1. HS 
Techn 
c 0.0 (1984 
S 
© 
Z 00 2. A. 
x Grain 
0.0 1986) 
3.R. | 
Ra \ Accel 
| a A Steel, 
0 : 4 5 6 7 8 9 0 11 
IQ 4.D. 
Figure 12: IQ multi-peak quantitative analysis of 1.0Al1 TRIP steel, Tia=770°C (60s), 15°C/s to 450°C, hot sts 
120s-AC. Recrystallized Ferrite= 48.31%, Non-RXD + New Ferrite= 31.33%, Bainite = 6.83%, 
Retained Austenite=9.86%, Martensite =3.67% 3. A. 
Quart; 
The final microstructure found after annealing at 770C, cooling to 450°C at 15°C/sec and air cooling to 
RT after a holding time of 120 sec at 450°C is shown in Figure 12 for the steel containing 1.0Al. The 6. H.C 
microstructure, revealed both by IQ-Multi-peak and supported by standard metallography, showed about Vol.1. 
48% recrystallized ferrite, 31% unrecrystallized ferrite (sum of old recovered and new ferrite), about 7% 
bainite, 10% retained austenite and 3.7% martensite. As indicated above, each of these features can be 7.E. 
observed and identified using standard techniques, but obtaining a quantitative estimate of the amounts 64 (1¢ 
of each is not possible in any other reliable wav AN 
Conclusions 
9. T.( 
From the time of Dube in the 1950s[20,21] to the present, researchers have known that ferrite and other 
microconstituents can assume many morphologies, depending on the composition and processing of 10. W 
steel. The various types of ferrite found in low carbon steel have been described in numerous papers, 
often with supporting illustrations and other documentation. It has been common for attempts to be 1.K 
made to quantify complex microstructures, using point counting and other standard quantifying 
techniques. However, these attempts are not satisfying because they are predicated on being able to 12. W 
distinguish among the different types of ferrite, which is, in fact, not possible based on conventional (Beiji 
metallography. In this paper, a new approach has been presented, the IQ-Multi-peak model, which 
allows the components of complex microstructures to be quantified. This technique, in its several forms, 13.J. 
reveals much information regarding the microstructure, itself, plus valuable information regarding the 
level and distribution of crystalline defects in the microstructure. Its application to real problems in 14. M