Structure of Iron-Based Cladding Layer on Al-Mg-Si Alloy Coated by a Resistance Seam Welding Method

Abstract

Iron-based cladding layers were successfully fabricated on the 2 mm thick Al-Mg-Si (A6061) alloys to improve the wear resistance of the substrate by a resistance seam welding (RSEW) method. Microstructure showed that the cladding layer consisted of the high carbon iron alloy powders (SHA) reinforcement, A6061 binder and Fe-Al phases. The Fe-Al phases had two kinds of micro-structured morphologies: a needlelike phase in the A6061 identified as FeAl 3 , and a planer transition phase at the A6061/SHA powders interface identified as Fe 2 Al 5 and FeAl 3 . A ball-on-disc test was carried out to evaluate the wear resistance of the cladding layers and the wear mechanism was discussed by observing the worn surfaces. Furthermore, the relationship of welding current and the microstructure, as well as the wear resistance of the cladding layer, were also investigated. The results showed that the wear resistance of the cladding layer increased with the increase of the welding current and the best wear performance was found at the welding current of 3.0 kA, where the wear rate was near two orders of magnitude less than the substrate. It was also suggested that the FeAl 3 in the cladding layer had a critical role to improve the wear resistance. Moreover, the wear mechanisms of the cladding layer changed from adhesion and delaminate to adhesion with the increase of the welding current.