PSI - Issue 71

Priti Kotak Shah et al. / Procedia Structural Integrity 71 (2025) 271–278

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2.2. Ring Tensile test RTT was carried out using a Screw Driven Universal Testing Machine (UTM) at a crosshead speed of 0.5 mm/min. The load-displacement data obtained from the test wereanalysed to get the stress-strain plot and the tensile properties of the clad. A special grip was used to hold these ring specimens to carry out tensile tests. The holding fixture consisted essentially of two half pieces of a mandrel, the curvature of which matched with that of the ring specimen. A photo of the RTT grip along with the sample specimen is shown in Fig. 1. 2.3. Ring Compression test RCT was also carried out using a Screw Driven Universal Testing Machine (UTM) at a crosshead speed of 1 mm/min. The load-displacement data obtained from the test were analysed to get the stress-strain plot and the compressive strength of the clad (Martin-Rengel, et.al. (2013)). For RCT, the test sample was held between the two flat surfaces of the top and bottom fixture to compress the sample as shown in Fig. 2.

Fig.1. Photo of ring tensile test grip shown with the sample in the grip before testing

Fig.2. Photo of ring compression test grip showing the sample, between two flat surfaces, before testing

3. Results and Discussions 3.1. Ring Tensile test

Typical stress-strain plots obtained from Ring Tensile Tests of different types of specimens are shown in Fig. 3. The ring tensile tested specimens along with an untested specimen are shown in Fig. 4. Mechanical properties, yield strength (YS), ultimate tensile strength (UTS), uniform elongation and break strain or total elongation, obtained from the analysis of the ring tensile test data have been plotted as bar chart and are shown in Fig. 5 to Fig. 7. Fig. 5 and 6 show the plot of Yield strength and UTS respectively for different types of clad specimens. It can be noted that rimmed hydrided clad specimens do not undergo any significant change as compared to the as fabricated clad tubes. However, for uniformly hydrided clad tubes, the yield strength first reduces on increasing the hydrogen concentration but for very high hydrogen concentration, it increases. Fig. 7 shows the break strain plot for different clad specimens. We see that for uniformly hydided specimens, the break strain reduces with increase in hydrogen concentration. The rimmed samples however do not show any change from as fabricated samples.