PSI - Issue 37

Jesús Toribio et al. / Procedia Structural Integrity 37 (2022) 1001–1006 Jesús Toribio / Procedia Structural Integrity 00 (2021) 000 – 000

1003

3

The test environment was an aqueous solution of 1 g/l calcium hydroxide plus 0.1 g/l sodium chloride. The pH of the solution was 12.5 and tests were performed at constant electro-chemical potential ranging between – 400 mV and – 1400 mV versus SCE ( saturated calomel electrode ): the former ( – 400 mV vs. SCE) is anodic and associated with environmental conditions promoting localized anodic dissolution (LAD) or pure stress corrosion cracking (SCC), whereas the latter one ( – 1400 mV vs, SCE) is cathodic and associated with environmental conditions promoting hydrogen assisted cracking (HAC) or hydrogen embrittlement (HE). The region of analysis is represented by a red line in the Pourbaix diagram shown in Fig. 2. Two testing rates ( applied displacement rates ) were used in the tests: one moderately fast (0.1 mm/min) and another moderately slow (0.01 mm/min).

Potential (mV SCE)

1.2

Passivation 3

0.6

Corrosion 1

0

Study region

-0.6

Immunity 2

-1.2

Corrosion

2 4 6 8 10 12 14

0

pH

Fig. 2. Pourbaix diagram and region of analysis.

3. Micro-fracture maps (MFMs) Fig. 3 shows the fracture surface and the micro-fracture map (MFM) for a commercial prestressing steel wire tested at the slow rate (0.01 mm/min) at a potential E = – 1200 mV SCE.

Fig. 3. Fracture surface and micro-fracture map (MFM).