Hybrid Friction Stir Welding Process with Plasma-assisted of 5052 H34 Aluminum Alloy and SAE 1020 Steel: Material Flow Characterization

Abstract:

This research dealt with the application of the Hybrid Friction Stir Welding process in dissimilar aluminum-steel welding using a plasma preheating source, in order to characterize the material flow. In this research, welded joints were made on top of SAE 1020 carbon steel and aluminum alloy 5052 H34 with 3 mm thickness using a head specially developed for this application, which was adapted to a COMAU NJ5000 anthropomorphic robot with 6 degrees of freedom and 500 kg capacity. The offset was kept at zero, in which the tool was inserted in the welding interface. The preheating of the samples was carried out by adapting a plasma cutting machine, in which the temperature and current were varied by: 0 ° C (without preheating), 250 ° C (40 A), 350 ° C (50 A) and 450 ° C (60 A). Microstructural characterization was performed using optical and scanning electron microscopy and X-ray diffraction (XRD). During the metallographic analyzes, the formation of a highly deformed region in the upper part of the samples submitted to preheating was identified and characterized, defined in this work as "head". This region offers an increase in the mechanical strength of the material, and will be as large as the greater for the heat input on the forward side. The material flow was determined, and it was possible to determine four possible geometries for the mixed zone, correlated with the mechanical strength obtained and conditions necessary to obtain each one.

Keywords:
Friction stir welding; Hybrid; Welding; Robotic; Dissimilar; Preheating