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ARPGE: a computer program to automatically reconstruct the parent grains from electron backscatter diffraction data.

Cayron C - J Appl Crystallogr (2007)

Bottom Line: A computer program called ARPGE written in Python uses the theoretical results generated by the computer program GenOVa to automatically reconstruct the parent grains from electron backscatter diffraction data obtained on phase transition materials with or without residual parent phase.The misorientations between daughter grains are identified with operators, the daughter grains are identified with indexed variants, the orientations of the parent grains are determined, and some statistics on the variants and operators are established.Variant selection phenomena were revealed.

View Article: PubMed Central - HTML - PubMed

Affiliation: CEA-Grenoble, DRT/LITEN, 17 rue des Martyrs, 38054 Grenoble, France.

ABSTRACT
A computer program called ARPGE written in Python uses the theoretical results generated by the computer program GenOVa to automatically reconstruct the parent grains from electron backscatter diffraction data obtained on phase transition materials with or without residual parent phase. The misorientations between daughter grains are identified with operators, the daughter grains are identified with indexed variants, the orientations of the parent grains are determined, and some statistics on the variants and operators are established. Some examples with martensitic transformations in iron and titanium alloys were treated. Variant selection phenomena were revealed.

No MeSH data available.


Related in: MedlinePlus

Martensitic steel (courtesy of J. M. Gentzbittel). (a) Orientation map of the martensite. (b) Reconstructed austenite (the boundaries of the martensitic grains are not shown here for better visibility). (c) Pole figures of some of the reconstructed austenitic grains with their calculated orientations (red spots) and with the experimental orientations of the martensitic grains (blue spots). (d) Statistical bar charts on the distributions of the variant indices and operator indices (the percentages of encountered variants or operators are given as a function of their indices).
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fig4: Martensitic steel (courtesy of J. M. Gentzbittel). (a) Orientation map of the martensite. (b) Reconstructed austenite (the boundaries of the martensitic grains are not shown here for better visibility). (c) Pole figures of some of the reconstructed austenitic grains with their calculated orientations (red spots) and with the experimental orientations of the martensitic grains (blue spots). (d) Statistical bar charts on the distributions of the variant indices and operator indices (the percentages of encountered variants or operators are given as a function of their indices).

Mentions: The third example is a martensitic steel used in nuclear pressured water reactors (courtesy of J. M. Gentzbittel, CEA-Grenoble, France). There is absolutely no residual austenite. The EBSD orientation map of the martensite is given in Fig. 4 ▶(a); the reconstructed austenite is presented in Fig. 4 ▶(b). More than 100 austenitic grains could be identified and their orientation determined. Some examples of the pole figures of the reconstructed austenitic grains are presented in Fig. 4 ▶(c). The reconstruction works even for small austenitic grains containing few martensitic grains (see grain 39 for example). The number of austenitic grains is enough to establish some statistics on the variant and operator indices, as illustrated in Fig. 4 ▶(d). The variant α1 is the most frequent because the programs always choose the index 1 for the larger grain during the nucleation process. In future versions of ARPGE we could attribute a random index between 1 and the theoretical number of variants to suppress this effect. It may be noticed that the most frequent operator is O3. This is a clear example of a variant selection phenomenon. Actually, this is not a surprise. The operator O3 corresponds to a rotation of 60° around the [110]α = [111]γ direction (Cayron et al., 2006 ▶); it links the three variants that share a common (111)γ plane (these three variants are also the ‘common’ variants for twinned austenite). The fact that the most frequent variants after the variant α1 are the variants α5 and α9 results from the high frequency of operator 3 (material property), the high frequency of the variant α1 (algorithm effect) and the fact that operator O3 contains the arrows α15 and α19 (theory).


ARPGE: a computer program to automatically reconstruct the parent grains from electron backscatter diffraction data.

Cayron C - J Appl Crystallogr (2007)

Martensitic steel (courtesy of J. M. Gentzbittel). (a) Orientation map of the martensite. (b) Reconstructed austenite (the boundaries of the martensitic grains are not shown here for better visibility). (c) Pole figures of some of the reconstructed austenitic grains with their calculated orientations (red spots) and with the experimental orientations of the martensitic grains (blue spots). (d) Statistical bar charts on the distributions of the variant indices and operator indices (the percentages of encountered variants or operators are given as a function of their indices).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2483492&req=5

fig4: Martensitic steel (courtesy of J. M. Gentzbittel). (a) Orientation map of the martensite. (b) Reconstructed austenite (the boundaries of the martensitic grains are not shown here for better visibility). (c) Pole figures of some of the reconstructed austenitic grains with their calculated orientations (red spots) and with the experimental orientations of the martensitic grains (blue spots). (d) Statistical bar charts on the distributions of the variant indices and operator indices (the percentages of encountered variants or operators are given as a function of their indices).
Mentions: The third example is a martensitic steel used in nuclear pressured water reactors (courtesy of J. M. Gentzbittel, CEA-Grenoble, France). There is absolutely no residual austenite. The EBSD orientation map of the martensite is given in Fig. 4 ▶(a); the reconstructed austenite is presented in Fig. 4 ▶(b). More than 100 austenitic grains could be identified and their orientation determined. Some examples of the pole figures of the reconstructed austenitic grains are presented in Fig. 4 ▶(c). The reconstruction works even for small austenitic grains containing few martensitic grains (see grain 39 for example). The number of austenitic grains is enough to establish some statistics on the variant and operator indices, as illustrated in Fig. 4 ▶(d). The variant α1 is the most frequent because the programs always choose the index 1 for the larger grain during the nucleation process. In future versions of ARPGE we could attribute a random index between 1 and the theoretical number of variants to suppress this effect. It may be noticed that the most frequent operator is O3. This is a clear example of a variant selection phenomenon. Actually, this is not a surprise. The operator O3 corresponds to a rotation of 60° around the [110]α = [111]γ direction (Cayron et al., 2006 ▶); it links the three variants that share a common (111)γ plane (these three variants are also the ‘common’ variants for twinned austenite). The fact that the most frequent variants after the variant α1 are the variants α5 and α9 results from the high frequency of operator 3 (material property), the high frequency of the variant α1 (algorithm effect) and the fact that operator O3 contains the arrows α15 and α19 (theory).

Bottom Line: A computer program called ARPGE written in Python uses the theoretical results generated by the computer program GenOVa to automatically reconstruct the parent grains from electron backscatter diffraction data obtained on phase transition materials with or without residual parent phase.The misorientations between daughter grains are identified with operators, the daughter grains are identified with indexed variants, the orientations of the parent grains are determined, and some statistics on the variants and operators are established.Variant selection phenomena were revealed.

View Article: PubMed Central - HTML - PubMed

Affiliation: CEA-Grenoble, DRT/LITEN, 17 rue des Martyrs, 38054 Grenoble, France.

ABSTRACT
A computer program called ARPGE written in Python uses the theoretical results generated by the computer program GenOVa to automatically reconstruct the parent grains from electron backscatter diffraction data obtained on phase transition materials with or without residual parent phase. The misorientations between daughter grains are identified with operators, the daughter grains are identified with indexed variants, the orientations of the parent grains are determined, and some statistics on the variants and operators are established. Some examples with martensitic transformations in iron and titanium alloys were treated. Variant selection phenomena were revealed.

No MeSH data available.


Related in: MedlinePlus