PSI - Issue 41

Ericha Dwi Wahyu Syah Putri et al. / Procedia Structural Integrity 41 (2022) 266–273 Putri et al. / Structural Integrity Procedia 00 (2022) 000 – 000

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Fig. 3. Schematic of SCC mechanism (crack growth rate vs. stress intensity)

3. Stress-Corrosion-Cracking Testing Methods 3.1. U-Bend Specimen

U-bend specimen has been widely applied in the qualitative assessment of SCC resistance of different alloys in different corrosive media. U-bend specimen testing method can be done using the ASTM G-30 standard practices (Jones et al., 2016). U-bend specimen is prepared by bending a strip 180 0 around a mandrel with a predetermined radius and using the U-bend horseshoe for constant specimen shapes (Bovard et al., 2011). The screw is inserted into the hole in the leg of the specimen. The last step, tighten the nut on the screw to load the specimen. Fig 4 shows that the specimen may be bent less than 180 0 . This method is widely used because it can produce many specimens, and it is suitable for qualitative assessment of alloy and heat treatment susceptibility to stress corrosion cracking (Krawczyk et al., 2018). Equation 1 is known to provide an approximation of applied strain ε : = 2 when < (1) Where t is the thickness of the specimen, and R is the radius of curvature at the point. When U-bend specimen is formed, the material in the outer fibers of the bend is strained into the plastic portion of the true-stress or true-strain curve.

Fig. 4. Preparation of U-bend specimen: (a) the distribution of welded joint; (b) the practical shape