PSI - Issue 13

Rui Guo et al. / Procedia Structural Integrity 13 (2018) 2202–2209 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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Figure 7 Von Mises stress distributions at the tip of the three different length cracks at the sampling position (a) a =4mm (b) a =5mm (c) a =6mm

The Y-direction tensile stress distribution of the three cracks at the sampling position is studied separately. The tensile stress distribution at the tip of the three different length cracks at the sampling position is shown in Fig. 8. As shown in Fig. 8, there is no obvious stress distribution boundary in the Y-direction tensile stress near the welded interface. When the crack length a is 4 mm is in the alloy 182 on the left side of the welding interface, the high tensile stress distribution area is small, as shown in Fig. 8(a). When a is 5 mm is at the welding interface, the distribution of the high tensile stress region of the crack tip is slightly larger than that of a =4 mm, as shown in Fig. 8(b). When the crack of a =6 mm is in the right side of the welding interface (A533B), the distribution of the high tensile stress region at the crack tip is larger than that of the other two materials, as shown in Fig. 8(c). By comparing Fig. 8(a)(b)(c), it can be seen that the welding interface of the base material A533B and the welding consumable 182 has little effect on the Y-direction tensile stress in the crack tip region of the welded structure, and the Von Mises stress around the crack tip increases with the growth of the crack length.

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Figure 8 Y direction tensile stress distributions at the tips of the three different length cracks at the sampling position (a)a=4mm (b)a=5mm (c)a=6mm Since the Von Mises stress and the Y-direction tensile stress near the crack tip are higher than the yield stress of the respective materials, the plastic strains caused by them are analyzed. The equivalent plastic strain distribution at the tip of the three different length cracks at the sampling position is shown in Fig. 9. As shown in Fig. 9(a), the crack length is 4 mm, and the equivalent plastic strain boundary is visible in the range of 1 mm radius around the crack tip when it is near the welding interface and in the weld material 182 alloy. The equivalent plastic strain distribution on both sides of the crack is not uniform, and the equivalent plastic strain on the side close to the welding interface is smaller. As shown in Fig. 9(b), the crack tip is on the welding interface, and the equivalent plastic strain distribution on both sides of the crack is not symmetric, the equivalent plastic strain in the alloy of the weld 182 in the lower is larger than that of the base material A533B. The material properties of base metal A533B and welding consumable 182 alloy are shown in Table 1. The yield stress and hardening exponent of A533B are higher than 182 alloy, so the material with higher strength has smaller equivalent plastic strain distribution. As shown in Fig. 9(c), when the crack propagates beyond the welding interface to A533B, the equivalent plastic strain boundary can be seen within 1 mm of the crack tip.