Local electrochemical properties of laser beam-welded high-strength Al-Zn-Mg-Cu alloys

摘要

Butt welds of two high-strength Al-Zn-Mg-Cu alloys with different zinc contents were welded by a laser beam welding technique. Due to the high energy density of the laser beam, the microstructural changes are confined to very thin regions. Electrochemical properties of the weld heat-affected zones are investigated by local electrochemical measurement techniques and correlated with microhardness measurements, macroscopic corrosion behaviour and metallographic sections. It turned out that microelectro-chemical techniques, especially the EC-pen is a versatile and easy to handle tool for the resolution of changes in the electrochemical properties across a weld bead. It unveils modifications, which cannot be resolved by hardness measurements. By microcell measurements, local corrosion kinetics can be estimated.