Modeling the effect of plate position on thermal, material flow and deposition during dissimilar friction stir welding between Al and Cu

Abstract

The effects of dissimilar Al/Cu plate position on thermal, material flow and deposition behavior in FSW are studied in detail based on computational fluid dynamics (CFD) simulation with bonding interface tracking by volume of fluid (VOF) technique. A novel 3D steady-state model is proposed to compare the coupled multi-physics fields between Type-I (Al-AS/Cu-RS) and Type-II (Al-RS/Cu-AS) positions. A 2D transient-state model with refined grid is established for the dynamic evolution of the periodic feature with Type-I position by considering tool eccentricity. It is found that the total heat input is identical with different plate positions, but the temperature around the pin is about 50–100 K higher with Type-II than that with Type-I. The flow streamline analyses indicate that direct-through flow pattern is dominated with Type-I, whereas both direct-through and multi-circle flow patterns are subsistent with Type-II. The tool eccentricity is confirmed to be the primary factor for the formation of the periodic feature in dissimilar Al/Cu FSW, since it changes velocity field around the tool and causes reciprocating block-open of the flow channel at the RS. The modeling results are in good agreements with abundant experimental observations.