Issue 78

A. Sancak et alii, Fracture and Structural Integrity, 78 (2026) 186-206; DOI: 10.3221/IGF-ESIS.78.11

°C. To evaluate the effect of notch timing, some specimens were notched before corrosion exposure, whereas others were notched after the corrosion exposure period. In this study, the term “notch timing” refers to the stage at which the standard Charpy V-notch was machined. For specimens notched after corrosion exposure, the specimens were first immersed in the corrosive medium in the unnotched condition and were then machined to introduce the V-notch before impact testing. For the pre-notched specimens, the Charpy V-notch was machined before immersion; therefore, the notch root was directly exposed to the corrosive medium during the exposure period. This comparison was designed to determine whether corrosion acting at the notch region influences the absorbed impact energy. The overall experimental matrix is summarized in Tab. 2.

Exposure duration

Test temperature

Group

Condition

Corrosion medium

Notch timing

1 2 3 4 5 6 7 8 9

Reference Reference Reference Reference Corroded Corroded Corroded Corroded Corroded Corroded Corroded

None None None None

None None None None

Before impact testing Before impact testing Before impact testing Before impact testing After corrosion exposure After corrosion exposure After corrosion exposure After corrosion exposure After corrosion exposure Before corrosion exposure Before corrosion exposure

23 °C

0 °C

− 20 °C − 40 °C

Seawater

10 days 10 days 30 days 30 days 30 days 30 days 30 days

0 °C 0 °C 0 °C 0 °C

Substitute seawater

Seawater

Substitute seawater

Seawater Seawater Seawater

23 °C

10 11

0 °C

23 °C Table 2: Experimental matrix used for corrosion exposure and Charpy V-notch impact testing.

Substitute seawater and seawater preparation Two corrosive media were used in the immersion experiments: substitute seawater and seawater. The substitute seawater was prepared according to ASTM D1141-98(2021), which defines the preparation of substitute ocean water [33]. The seawater was collected from the Üsküdar coastal region of İ stanbul, Türkiye. The use of both media enabled a comparison between a standardized laboratory seawater solution and a coastal seawater environment. The substitute seawater was prepared at room temperature using distilled water and reagent-grade salts. Two stock solutions were first prepared separately. Stock solution I contained MgCl ₂ ·6H ₂ O, anhydrous CaCl ₂ and SrCl ₂ ·6H ₂ O, while stock solution II contained KCl, NaHCO ₃ , KBr, H ₃ BO ₃ and NaF. Concentrations of the stock solutions are given in Tab. 3.

Stock solution

No.

Compound

Concentration

MgCl ₂ ·6H ₂ O

I

1

555.6 g/L

CaCl ₂ , anhydrous

I

2

57.9 g/L

SrCl ₂ ·6H ₂ O

I

3

2.1 g/L

II

4

KCl

69.5 g/L

NaHCO ₃

II

5

20.1 g/L

II

6

KBr

10.0 g/L

H ₃ BO ₃

II

7

2.7 g/L

II 0.3 g/L Table 3: Chemical compounds used for the preparation of substitute seawater stock solutions. 8 NaF

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