A new device for simultaneous corrosion fatigue testing of joined materials in accelerated corrosion tests

Fatigue performances of joined samples are classically evaluated by performing fatigue tests, generally in ambient air while corrosion-fatigue studies of joined panels may be conducted in water, salt solution or humid air. However, the evaluation of combined fatigue and corrosion performance of joined materials is not well documented, in particular when considering accelerated corrosion tests. Hence, a device that allows fatigue corrosion to be performed on joined panels in cyclic corrosion tests has been developed. Lap-shear type panels involving cold rolled steel (CRS), hot dip galvanized steel (HDG) or aluminium joined together using either spot-welding, adhesive bonding, clinching or combination of spot-welding or clinching with adhesive bonding were tested in an accelerated corrosion test as per VDA 233-102, with and without simultaneous fatigue loading. Some of the samples were tested unpainted while others were electrocoated. The data were also compared with fatigue resistance in air. The results indicated that the damaging effect of corrosion was in general increased by the simultaneous fatigue loading compared to pure corrosion tests, particularly on adhesive bonded materials. An effect of corrosion on the fatigue resistance of clinched and clinch-bonded samples was only observed when the frequency of the fatigue loading was lowered from 0.5 to 0.25 Hz. Weld-bonded samples presented no failure during corrosion-fatigue tests, as well as spot-welded samples.