PSI - Issue 68

Mahmoud Khedr et al. / Procedia Structural Integrity 68 (2025) 1017–1023 Mahmoud Khedr / Structural Integrity Procedia 00 (2025) 000–000

1022

6

Moreover, the mechanical strength of welded joints was lower than the MMn-SS and NiCr-SS. However, the mechanical strength of welded joints was slightly higher than that of the LCS. Furthermore, the fracture of welded tensile specimens happened on the LCS side because the filler metal has an ultimate tensile strength higher than the LCS as shown in Figure 6.

Table 3. Tensile properties of studied steels and welded metals.

Tensile properties

Location of fracture

Materials LCS-BM

YS, , MPa

UTS , MPa

El.% 26.3 47.4 58.6 14.7 15.2

305±5 480±5 300±5 328±7 325±5

362±7 915±10 738±10 365±10 380±1

Gauge length Gauge length Gauge length

MMn-SS-BM NiCr-SS-BM LCS/MMn-SS LCS/NiCr-SS

LCS-BM LCS-BM

Figure 5. Stress-strain curves for base metals and welded joints at strain rate 10 -3 s -1 .

Figure 6. Photograph of the tensile specimens showing the location of the fracture of LCS/MMn–SS and LCS/NiCr-SS welded joints.

3.4. Fractography Figure 7 shows the fractography of tensile specimens from the dissimilar LCS/MMn-SS and LCS/NiCr-SS welded joints. Both welded joints exhibit dimple features, which are typical characteristic features of a ductile fracture. This can be attributed to the significant plastic deformation that the butt joints experienced prior to failure, as illustrated in Figure 5.