Aluminium structures become more and more popular in industries thanks to their light weights. Moreover, welding of cast aluminium hollow parts is a new promising technical trend for structural assemblies [1-3]. In this paper, the aluminium A356 cast tube welding is studied. Square tubes are made of A356 by sand casting and then machined. They are assembled by four MIG welds, named W1 to W4. Their dimensions and the welding setup are depicted in Figures 1-2.

Figure 1  Tube welding configuration: a) cross-section view, b) tube dimensions

Figure 2  Experimental setup for tube welding

The distortion of the welded assembly was predicted by numerical simulations using the finite element software Sysweld [4]. The heat source parameters were identified based on the metallographic cross-section as shown in Figure 3. The numerical results of the distortion, as depicted in Figure 4, were then validated with experimental results. A very good agreement was obtained between the numerical simulations and experimental results both in distortion tendency and distortion range as given in Table 1.

a)	b)

Figure 3  (a) Metallographic cross-section, (b) Melting pool cross-section

Figure 4  Numerical results of the distortion of the welded assembly

Table 1  Distortion result comparison

  References

1.	Von Zengen K-H., “Aluminium in future cars – A challenge for materials science”, Materials Science Forum, Vol. 519-521 (Part 2), pp. 1201-1208, 2006.
2.	Wiesner S., Rethmeier M. and Wohlfart H. , “MIG and laser welding of aluminium alloy pressure die cast parts with wrought profiles”, Welding International, 19 (2), pp. 130-133, 2005.
3.	Akhter R., Ivanchev L., Rooyen C.V., Kazadi P. and Burger H.P., “Laser welding of SSM Cast A356 aluminium alloy processed with CSIR-Rheo technology”, Solid State Phenomena, Vol. 116-117, pp. 173-176, 2006.
4.	Sysweld, “Sysweld reference manual”, ESI Group, 2005.