Limits...
Determination and mitigation of the uncertainty of neutron diffraction measurements of residual strain in large-grained polycrystalline material.

Holden TM, Traore Y, James J, Kelleher J, Bouchard PJ - J Appl Crystallogr (2015)

Bottom Line: For large-grained samples it is advantageous to perform pairs of neutron diffraction measurements at the same spatial location but rotated 180° around the geometric centre of the gauge volume as a means of minimizing the scatter coming from the random positioning of grains within the gauge volume.

View Article: PubMed Central - HTML - PubMed

Affiliation: Engineering and Innovation, The Open University , Walton Hall, Milton Keynes MK7 6AA, UK.

ABSTRACT

For large-grained samples it is advantageous to perform pairs of neutron diffraction measurements at the same spatial location but rotated 180° around the geometric centre of the gauge volume as a means of minimizing the scatter coming from the random positioning of grains within the gauge volume.

No MeSH data available.


Related in: MedlinePlus

Deviations from the average lattice parameter, expressed in the form Δa/a, for 48 measurements (top) and 24 pairs (bottom) for the Type 316L austenitic stainless steel. The average lattice parameter was 3.59500 Å and the standard deviations, expressed as a strain, were 84 and 42 × 10−6, respectively.
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fig2: Deviations from the average lattice parameter, expressed in the form Δa/a, for 48 measurements (top) and 24 pairs (bottom) for the Type 316L austenitic stainless steel. The average lattice parameter was 3.59500 Å and the standard deviations, expressed as a strain, were 84 and 42 × 10−6, respectively.

Mentions: Fig. 2 ▶ shows the distribution of offsets about the average value of the lattice parameter, expressed in the form Δa/a, as a function of position along the reference cylinder for all 48 measurements for the large-grained 316L austenitic stainless steel and the 24 averages of pairs of values. The average lattice parameter and standard deviation are noted. The standard deviation is reduced by 50% for the pairs. Fig. 3 ▶ presents similar results for the Alloy-52 weld metal, which had a columnar grain structure. Fig. 4 ▶ illustrates the distribution of offsets about the average lattice parameter for the 40 measurements of strain for the ferritic steel. In this case, the standard deviation only decreases by about 5%. A minor difference between the two counter banks [24 (12) × 10−6] can be discerned, but this is far less than the offsets for the large-grained material. For the ferritic material there is a maximum variation in lattice parameter, expressed as a strain between the outside and inside surfaces of the pipe of 40 × 10−6.


Determination and mitigation of the uncertainty of neutron diffraction measurements of residual strain in large-grained polycrystalline material.

Holden TM, Traore Y, James J, Kelleher J, Bouchard PJ - J Appl Crystallogr (2015)

Deviations from the average lattice parameter, expressed in the form Δa/a, for 48 measurements (top) and 24 pairs (bottom) for the Type 316L austenitic stainless steel. The average lattice parameter was 3.59500 Å and the standard deviations, expressed as a strain, were 84 and 42 × 10−6, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4379440&req=5

fig2: Deviations from the average lattice parameter, expressed in the form Δa/a, for 48 measurements (top) and 24 pairs (bottom) for the Type 316L austenitic stainless steel. The average lattice parameter was 3.59500 Å and the standard deviations, expressed as a strain, were 84 and 42 × 10−6, respectively.
Mentions: Fig. 2 ▶ shows the distribution of offsets about the average value of the lattice parameter, expressed in the form Δa/a, as a function of position along the reference cylinder for all 48 measurements for the large-grained 316L austenitic stainless steel and the 24 averages of pairs of values. The average lattice parameter and standard deviation are noted. The standard deviation is reduced by 50% for the pairs. Fig. 3 ▶ presents similar results for the Alloy-52 weld metal, which had a columnar grain structure. Fig. 4 ▶ illustrates the distribution of offsets about the average lattice parameter for the 40 measurements of strain for the ferritic steel. In this case, the standard deviation only decreases by about 5%. A minor difference between the two counter banks [24 (12) × 10−6] can be discerned, but this is far less than the offsets for the large-grained material. For the ferritic material there is a maximum variation in lattice parameter, expressed as a strain between the outside and inside surfaces of the pipe of 40 × 10−6.

Bottom Line: For large-grained samples it is advantageous to perform pairs of neutron diffraction measurements at the same spatial location but rotated 180° around the geometric centre of the gauge volume as a means of minimizing the scatter coming from the random positioning of grains within the gauge volume.

View Article: PubMed Central - HTML - PubMed

Affiliation: Engineering and Innovation, The Open University , Walton Hall, Milton Keynes MK7 6AA, UK.

ABSTRACT

For large-grained samples it is advantageous to perform pairs of neutron diffraction measurements at the same spatial location but rotated 180° around the geometric centre of the gauge volume as a means of minimizing the scatter coming from the random positioning of grains within the gauge volume.

No MeSH data available.


Related in: MedlinePlus