EBSDEBSD Steel DatasheetDatasheet part # 51-H5-057

Related to sample part # 51-H5-056

IntroductionOxford Instruments supplies an electro-polished austenitic stainless steel sample with every new EBSD system to assist you with getting started with EBSD data acquisition and post-processing. This report provides guidelines for acquiring and analysing EBSD data using this sample. For more detailed instructions please refer to the manuals provided with the system.

Sample Details and Preparation This sample, extracted from a sheet of austenitic stainless steel, was mechanically planed and electro-polished in the central region

as shown by the optical image in Fig. 1a. The electro-polishing was conducted using electrolyte A3 at 14°C and 30 V. Fig.1b is

a schematic diagram of the sample, where the cut corners give reference to the rolling (RD) and transverse (TD) directions. As

shown by Fig. 1c, in this analysis, the sample was mounted in the SEM, so that the RD was aligned to the SEM stage tilt axis and

the cut corners were on the right hand side of the sample as seen by the EBSD detector. We recommend that you mount the

sample in the same way so that your orientation data can be compared directly to that presented later in this report.

Fig. 1a. Optical image of the sample – the sample length is approximately 5 mm.

Fig. 2. An FSD image of the sample acquired at 70º tilt.

If your Nordlys detector is fitted with forward

scatter diodes (FSD), this type of image can be

collected using the lower two diodes and is useful

for showing orientation contrast, giving you an idea

of the step size you need to use to resolve the grains

satisfactorily. If your Nordlys detector also has the

upper diodes fitted, these can be used for showing

atomic number contrast and identifying where the

different phases lay in the sample.

Fig.1b. Schematic diagram of the sample dis-playing the rolling and transverse directions with respect to cut corners.

Fig.1c. Schematic diagram of the sample position relative to the EBSD detector.

TD

RD

Tilt axis

250 mm

EBSD Analysis

The data presented in this datasheet was collected using the Oxford Instruments AZtecHKL EBSD system with a NordlysMax2

EBSD detector.

Prior to EBSD mapping, the major constituent phases in the sample should be identified using the EBSD and / or EDS system. This

sample only contains austenitic steel which can be indexed using the iron FCC phase from the HKL Phases database. An example

of a typical EBSD pattern is shown in Fig. 3a. Fig. 3b, shows how this EBSP can be correctly indexed using the Iron FCC phase.

The conditions used to acquire the EBSD data presented here are given in Table 1. However, it is not necessary to use identical

settings, although you should ensure that the area mapped includes sufficient grains in order to get reasonable statistics.

Raster 1069 x 801 pixels

Step size 1.0 μm

Solver Refined Accuracy

Number of Bands 12

Hough Resolution 70

EBSD Camera Binning Mode 6 x 6

EBSD Camera Gain 3

Hit rate 98.4% Table 1: EBSD acquisition settings.

Fig. 3a: Background corrected EBSP. Fig. 3b: Indexed EBSP.

EBSD Steel Datasheet

2 EBSD Steel Datasheet

Fig. 4. EBSD Grain boundary and Inverse Pole Figure (IPF) map. IPF map component along the Normal Direction (or Z axis) with the corresponding legend.

Fig. 5. Set of {100}, {110} and {111} contoured stereographic pole figures.

The collected raw data was exported into Channel5 format where it could be analysed using the post processing tools Tango

(maps) and Mambo (pole figures), however similar analysis can also be done in AZtec. Initially, the data was examined in Tango

and processed to remove isolated errors (wild spikes) and reduce the number of zero solutions, via extrapolation. The resulting

data is shown in Fig. 4 as an inverse pole figure (IPF) map along the normal plane (z axis) with the colouring given in the legend.

Grain boundaries are also shown on this map; the high angle boundaries are shown in black and the twin boundaries are shown

in red.

This map is a convenient way of quickly presenting the microstructure orientation in terms of the sample coordinates, given

in Fig. 1b. The colour scheme reflects the orientation superimposed on the EBSP band contrast (quality) map and shows that

a large fraction of the grains have a preference for the 110 orientation (green colour) – i.e. there is a preference for the {110}

planes to lie in the sheet plane which is perpendicular to the ND (Z-axis).

Crystallographic texture, which is defined as the preferred orientation of the crystal lattices (i.e. grains within a material) , can

also be represented as stereographic projections using pole figures. The associated set of {100}, {110} and {111} contoured

pole figures are shown in Figure 5. The {110} pole figure confirms the existence of a higher number of {110} planes lying

perpendicular to the normal direction than in the other directions.

Datasheet part # 51-H5-057

Related to sample part #: 51-H5-056EBSD

200 mm

EBSD Steel Datasheet 3

The materials presented here are summary in nature, subject to change, and intended for general information only.Performances are configuration dependent. Additional details are available. Oxford Instruments NanoAnalysisis certified to ISO9001, ISO14001 and OHSAS 18001. AZtec is a Registered Trademarks of Oxford Instruments plc,all other trademarks acknowledged. © Oxford Instruments plc, 2016. All rights reserved. Document reference: OINA/EBSD Steel Datasheet/0416.

www.oxford-instruments.com/EBSD

3.5 nm

Grain Detection can be used to reconstruct individual grains in an EBSD map. Once this has been done various parameters

including the grain diameter, area and aspect ratio can be determined.

In this study, a grain was defined as a region of ten or more pixels being completely surrounded by boundaries that have

a misorientation angle larger than a critical value of 10° (shown by the black lines in Fig. 4). Furthermore, the special twin

boundaries (60º misorientation around the 111 axis) shown by the red lines in Fig. 4, were excluded as they may be considered

part of the parent grains.

Once the grain parameters had been defined and the grains detected, a summary of the statistics for the grains is given in the

Grain Statistics window, which displays statistical information about the grain reconstruction parameters. As can be seen from

Table 2, in this example, ~1900 grains were analysed with an average grain size of ~20 μm. Note that the grain size may vary

from the value given here due to statistical variation of the number of grains.

Average, Expectation 20.0

Standard Deviation 11.5

Minimum Value 3.6

Maximum Value 83.5

Number of Grain (not including border grains) 1888Table 2: The grain size statistics.

ConclusionIn this report, a brief EBSD analysis has been presented for the Austenitic Steel sample provided with your EBSD system. It details the methodology of acquiring the EBSD map data and describes how the microstructure was interpreted in terms of texture and average grain size.

Meanwhile, the contoured IPF for the RD shown in Fig. 6, is

a typical example of a rolling texture as would be expected

given that the sample is cut from a rolled sheet and the

alignments are as indicated in Fig. 1b.

Fig. 6: Inverse pole figure showing a high intensity

of {111} planes parallel to the RD.