Prakt. Met. Sonderband 38 (2006) 43 
> Proc. 41st EBSD ANALYSIS OF THE RECRYSTALLIZATION BEHAVIOUR 
OF THE NICKEL BASED ALLOY 80 A DURING HOT FORMING 
w-Hill. S. Mitsche*, C. Sommitsch**, P. Polt* 
uctures of IF Institute for Electron Microscopy, Graz University of Technology, Graz, Austria 
Is XIV With * Christian Doppler Laboratory for Materials Modelling and Simulation / Chair of Metal 
05: Materials Forming, University of Leoben, Leoben, Austria 
rength, Low- ABSTRACT 
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te and Roger The dynamic recrystallization as well as meta-dynamic and static recrystallization of the 
5), 77-86. nickel based alloy 80A was investigated by means of electron backscatter diffraction. 
Specimens were hot compressed at a temperature of 1120°C and a strain rate of 0.1/s at 
both varying strain and soak times to describe the recrystallization behaviour. The grain 
orientation spread was used in order to distinguish between recrystallized and non 
v, Pittsburgh, recrystallized grains from EBSD data. A high twinning of the recrystallized grains was 
observed and as a consequence the measured grain size was strongly dependent on the 
consideration of the twins 
545 
1. INTRODUCTION 
Recrystallization of metals and alloys can take place due to hot deformation or due to cold 
working followed by annealing processes and is often used to tune the properties of the 
respective material. The recrystallization process predominantly changes the 
microstructure and therefore the mechanical properties and formability of the materials, 
whereas there are only slightly changes of the physical properties [1]. 
The determination of the recrystallized fraction can be performed with several methods. 
The simplest one is to measure the micro-hardness, which significantly decreases during 
the early stage of recrystallization [2]. Gerber et al. [3] demonstrated that for copper x-ray 
diffraction is also a suitable technique to investigate the recrystallization process. 
Traditionally, optical microscopy has been used to distinguish between the deformed and 
the recrystallized fraction [4]. The advantage of this technique is the possibility to 
investigate large areas of a specimen within a relatively short time obtaining good 
statistical results. But Poelt at el. [5] showed that for a nickel based alloy this technique is 
limited to specimens with lower strain. 
Electron backscatter diffraction (EBSD) in the scanning electron microscope (SEM) has 
appeared as a powerful tool to measure the size, the distribution and volume fraction of 
deformed and recrystallized grains because of its capability to obtain information of 
individual grains and to establish direct neighbourhood relationship between these grains 
[6, 7]. Different approaches are suggested to differentiate between the recrystallized and 
deformed grains from EBSD datasets [8-11] depending on the used material. 
In this paper the orientation spread is used because of its successful utilisability to 
discriminate between recrystallized and deformed grains from EBSD data [12]. 
Additionally, the behaviour of dynamic (DRX), metadynamic (MDRX) as well as the static 
recrystallization (SRX) of this nickel alloy is examined by using pre-deformed specimens.