PSI - Issue 47

Christoph Bleicher et al. / Procedia Structural Integrity 47 (2023) 478–487 Author name / Structural Integrity Procedia 00 (2019) 000–000

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All materials were cast in blocks with 1000 mm x 600 mm x 200 mm The chemical compositions of all three materials in sound condition are given in Table 1. While the silicon content was elevated by about 1 % to achieve a solid-solution strengthening effect for EN-GJS-450-18 a higher copper content was used to provoke a pearlitic microstructure in EN-GJS-700-2. After casting the blocks a groove was milled in the cast blocks, Fig. 1. The geometry of the groove was chosen similar to typical grooves that are produced in the foundries to rework a surface-near defect.

Table 1. Chemical composition of the investigated materials EN-GJS-400-18LT Chemical Composition (in %-weight) C Si Mn Cr S Ni Mg

Cu

3.72

1.97

0.20

0.03

0.01

0.01

0.044

0.02

EN-GJS-450-18 Chemical Composition (in %-weight)

C

Si

Mn 0.20

Cr

S

Ni

Mg 0.05

Cu

3.36

2.93

0.03

0.01

0.02

0.02

EN-GJS-700-2 Chemical Composition (in %-weight)

C

Si

Mn 0.40

Cr

S

Ni

Mg 0.05

Cu

3.66

1.89

n. d.

0.01

n. d.

1.06

n. d. – not determined

Fig. 1 Machined cast blocks with a V-shaped groove for the removal of axial specimens

After the preparation the cast blocks were welded with different dissimilar welding fillers in hot and cold condition. In preliminary investigations at project partners it turned out that a cold welding and hand welding process based on the welding filler CastoMag 45640 Ti showed the best results for EN-GJS-400-18LT and EN-GJS-700-2. Much more afford needed to be spent on the high silicon EN-GJS-450-18 due to crack formation in the fusion line. The cast iron grade showed a behavior during welding comparable to EN-GJS-500-14 inspected by Holdstock (2023). Nevetheless, best results were obtained by the welding filler EnDoTec Do 23. During the reported investigations no special focus was set on the further development of the welding procedure or the welding filler itself. As it was done in Bleicher (2022) for the cyclic material investigations, different unnotched axial specimens with a test diameter d of 6 and 9 mm (Fig. 2) and bending specimens were machined from the cast blocks for fatigue investigations. The specimens with diameter d = 6 mm were taken from the base material a directly compared to the results of the specinens with a diameter of 9 mm. This so called “integral” fatigue specimen was machined across all these zones which are the base material, the heat-affected zone and the welding filler. The removal plan for the integral fatigue specimen is given in Fig. 3. Additionally bending specimens (Fig. 4) were removed from additional cast blocks to determine the fatigue behavior of the integral material state in combination with a superposed stress gradient as it might occur on large cast wind energy components. The bending specimens were chosen comparably large to achieve a small stress gradient in the specimens typical for large components.