Research on salt spray corrosion of DM code laser-marked on aluminium alloy

In order to improve the corrosion resistance of Data Matrix (DM) code laser marked on aluminum alloy, the salt spray corrosion resistance was determined. First, the corrosion resistance of DM code laser marked by 3 different processing modes was investigated. Meanwhile, the SEM images and EDS data for modules and substrate of DM code are analyzed, which explains the differences of corrosion resistance for DM code by the 3 processing modes. A kind of laser combined electrochemical marking method for anti-corrosion DM Code mark was put forward, where a bare mark of DM code was created by direct laser marking in advance, and then a uniform, compact and protective oxide film was deposited on the bare mark by electrochemical oxidation to form the corrosion resistant mark. The results show that the corrosion resistance of laser direct marking DM code for different processing modes exist some difference. However, all the DM code samples become failure after at most 15.5 hours salt spray corrosion. The DM Code mark by the proposed method can withstand approximately 42 hours of salt spray corrosion, whose corrosion resistance improved 2-3 times.