Hybrid Friction Stir Welding Process with Plasma-assisted of 5052 H34 Aluminum Alloy and SAE 1020 Steel: Analysis of Mechanical Strength, Tool Wear and Welding Stresses

Abstract:

This research addressed the first application of the Hybrid Friction Stir Welding process using plasma preheating source in aluminum-steel welding. One of the benefits of using joint preheating is the possibility of coalescing the material and reducing its mechanical resistance, thus making possible the use of tools made of steel, in addition to making the mixing more efficient by introducing the tool directly into the welding interface. In this research, welded joints of SAE 1020 carbon steel and aluminum alloy 5052 H34 with 3 mm thick plates were made using a specially designed head for this application, which was adapted to a COMAU NJ5000 anthropomorphic robot of 6 degrees of freedom and capacity of 500 kg. The samples were preheated by the adaptation of a plasma cutting machine, where the temperature and the current were varied in: 0 °C, 250 °C (40 A), 350 °C (50 A) and 450 °C (60 A). The displacement of the tool (offset) was varied in zero and -2.5 mm. The increase in the mechanical strength of the joints with the increase of the preheating temperature was identified. When the preheating temperature was 450 °C there was an approximately 111% increase in mechanical strength compared to the process without preheating. It has been possible to reduce welding efforts and tool wear by increasing the preheat temperature.

Key-words:
Friction stir welding; Hybrid; Welding; Robotic; Dissimilar; Preheating