HRDIC dataset of strain localization in shot peened Ni superalloy
| Main Authors: | Orozco-Caballero, Alberto, Quinta da Fonseca, João |
|---|---|
| Format: | info dataset Journal |
| Bahasa: | eng |
| Terbitan: |
, 2021
|
| Subjects: | |
| Online Access: |
https://zenodo.org/record/4728016 |
Daftar Isi:
- We used high-resolution digital image correlation (HRDIC) to measure strain distribution at each deformation step near the shot peened surface of a Ni superalloy, deformed in tension at 450 C. To make the DIC analysis possible, we first developed a fine, homogeneous distributed gold speckle pattern by remodelling a thin gold layer previously deposited on the polished sample surface. The gold layer was deposited using an Edwards S150B sputter coater for 4 minutes providing a ~40-45 nm thickness gold layer. Then, the sample was placed in the heating plate of the remodelling device for 6 hours at 300 °C. During the remodelling process, water vapour flows onto the surface of the coated material and remodels the gold layer into fine speckles. In order to avoid any possible speckle coarsening during the high temperature tensile testing, the remodelled sample was heated in a furnace at 475 °C for 5 hours and air cooled to stabilise the gold pattern. Due to the required stabilization heat treatment, the average speckle size was 120 nm, which is coarser than in previous studies at room temperature, where no pattern thermal stabilization is needed. We used a FEI Magellan HR 400L FE-SEM with a theoretical resolution of ≤ 0.9 nm at <1kV to take backscattered electron images of the pattern. The images were obtained at a working distance of 3.5 mm, 5 kV and 0.8 nA beam current. Mosaics of 30x15 images were used to cover 950x420 squared microns, an area shown area in Fig. 1). Each image contains 2048 x 1768 pixels and has a horizontal field of view of 43 microns. The images were overlapped by 20% to enable easy stitching prior to the digital image correlation. We obtained 7 mosaics, one before tensile testing and 6 after each deformation step. The mosaics for the un-deformed and deformed state were correlated using LaVision’s digital image correlation (DIC) software (version DaVis 8.3). The correlation was performed using a sub-window size of 1616 pixels and no overlap, which provides a spatial resolution of about 335 nm. This resolution allowed us to handle the large data sets generated when covering such large areas (each mosaic was 45.5k x 20k pixels in size). The correlation produces full-field in-plane displacement maps u(x1, x2, 0) on the plane x1x2 with normal x3. Code for reading and visualizing this data is available here: https://doi.org/10.5281/zenodo.4727939. The shear strain data is also provided as a python dictionary saved as a NumPy array. Visualization previews are given as .png and .gif files.