PSI - Issue 17

Liting Shi et al. / Procedia Structural Integrity 17 (2019) 355–362 Jidong Kang/ Structural Integrity Procedia 00 (2019) 000 – 000

360

6

τ HAZ (MPa)

τ nugget (MPa)

τ IMC (MPa)

τ HAZ / τ nugget

τ HAZ / τ IMC

Al thickness reduction （ % ）

Weld nugget diameter (mm) Fracture load (N)

Aluminum

Aluminum or steel

0.8-mm X626

0.8-mm X626

5.2±2.1

6.2±0.2

2430±494 189±3.1 96±5.0

-

2.0

1.2-mm AA6022

1.2-mm AA6022

14.5±2.0

6.2±0.1

3415±121 178±8.4 87±12

-

2.0

0.9-mm LCS

8.1±1.3

7.5±0.1

2907±190 189±3.1

-

79±10

-

2.4

0.8-mm X626

1.2-mm LCS

4.0±0.5

8.2±0.1

4253±202 178±8.4

-

91±8

-

2.0

1.2-mm AA6022

Based on the experimental results in Table 3, the critical weld nugget diameter and corresponding fracture loads were calculated using the new formulas. The predicted and experimental results were compared as shown in Fig. 6. The filled symbols represent the experimental interfacial fracture and the open ones represent the experimental pull out fracture mode from the tensile shear tests. The critical weld nugget diameter and corresponding calculated fracture loads are also presented in Fig. 6 where the interfacial fracture zone and pull put fracture zone are separated using dashed lines. When the weld nugget diameter was larger than the critical weld nugget diameter, i.e. the region outside of the dashed line in Fig. 6 (a)-(d), the fracture modes were pull out. In contrast, the zone inside the dashed line represents interfacial fracture. Analogous results predicted by the AWS method were also plotted in Fig. 6 for comparison.

Fig. 6 Prediction of fracture modes using present method and method recommended by AWS, (a) 0.8-mm X626-0.8-mm X626, (b) 1.2-mm AA6022-1.2-mm AA6022, (c) 0.8-mm X626-0.9-mm HDG LCS and (d) 1.2-mm AA6022-1.2-mm HDG LCS. The filled symbols represent the interfacial fracture and the open symbols represent the pull out fracture mode recorded from the experiments.

From Fig. 6 it can be observed that the AWS method under-estimated the critical weld nugget diameter required to