Oblique cross-section nanoindentation for determining the hardness change in ion-irradiated steel

Comparative Study of Two Nanoindentation Approaches for Assessing Mechanical Properties of Ion-Irradiated Stainless Steel 316

“…This was achieved after aligning all the samples to the reference of zero depth at the first indent on the epoxy-sample interface. The resulting ΔH-depth profiles for the sample irradiated with 1, 2, and 3 MeV He to a fluence of 1 × 10 17 ions/cm 2 are given in Figure 4b [15]. Some observations that can be made from this graph are:…”

“…The model results underestimate the hardness in the shoulder region with a larger gradient close to the metal-epoxy interface. The model captures the position and magnitude of the peak hardness accurately after correction of the ISE of the unirradiated region as per the work of Pöhl et al [24] and outlined in the author's earlier study [15]. Conversely, for the top-down method, Figure 8b, we observe a broad hardness peak, both in the experiments and the simulation results, whereby the model slightly over-predicts the depth position at peak hardness (100-130 nm) and the magnitude of the hardness difference.…”

“…Here, the authors attempt to compare the efficacy of the two methods mentioned above in studying the relationship between the calculated depth of peak damage and the corresponding depth of hardness peak as a function of ion irradiation energy. A finite element model, developed by the authors in previous works [14,15] for both nanoindentation methods has been used to understand the deformation behaviour in the plastic zone below the indents. The nature of the dependence of measured hardness on indentation depth vis-à-vis the ion beam energy is discussed for both methods, and appropriate ranges of applicability for each method are suggested based on the experimental results and analysis.…”

“…Damage profiles of He in stainless steel 316. Reproduced from[15], with permission from Elsevier Publishing, 2018.…”

“…Experimental and FEA modelling results for (a) oblique cross section method for hardness difference variation with depth in sample (Reproduced from[15] with permission from Elsevier Publishing, 2018) and (b) top-down method for the change in hardness with indent depth for 2 MeV He 2+ irradiated sample.…”