PSI - Issue 18

Ibrahim Al Zamzami et al. / Procedia Structural Integrity 18 (2019) 255–261 Author name / Structural Integrity Procedia 00 (2019) 000–000

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The steel sheet was coated with a layer of zinc approximately 25 µm thick. For the fatigue testing, the specimens were manufactured using two different sheet thickness (1 mm and 2mm) to be tested under different fatigue load ratios (R= -1, R= 0.1 and R= 0.5). The chemical compositions of the investigated materials are summarized in Table 1. Figure 1 displays the welded joint configurations to be tested including butt-welded, cruciform-welded, lap-welded and tee-welded joints, which were manufactured using EWM alpha Q551 Pulse machine to investigate the fatigue strength of the hybrid-welded joints. It is worth mentioning that the galvanized steel sheet is only coated with zinc on the top and bottom surfaces. Hence, for the butt-welded joints, there is a lack of fusion between the ends of aluminium and steel plates and the weld only acts as a bridge over the butt interface to hold the two materials together.

Table 1. Mass chemical composition of the used materials by weight percentage.

Alloy

Chemical composition [weight%]

AA1050

Cu

Mg

Si

Fe

Mn

Zn

Ti

Al

0-0.05

0-0.05

0.25

0-0.4

0.05

0.07

0-0.05

Balanced

EN10130:199

C

P

S

Mn

Fe

0.12

0.045

0.045

0.60

Balanced

AA4043

Cu

Mg

Si

Fe

Mn

Zn 0.1

Ti

Al

0.01

0.05

4.5-6.0

0.80

0.05

0.2

Balanced

A MAYSE dynamic machine with 100 kN capacity was used to perform the fatigue tests at room temperature. The samples were at a frequency of 10 Hz, in the as welded condition. During fatigue testing, the clear distance between the grips and the weld seam is always kept approximately 20 mm to prevent the presence of any secondary bending effect.

(a)

(b)

(c)

(d)

Fig. 1. Geometry of the investigated aluminium-to-steel: (a) welded butt-welded joints; (b) cruciform welded joints; (c) lap-welded welded joints; (d) tee welded joints.