Effect of Different Tool Probe Profiles on Material Flow of Al-Mg-Cu Alloy Joined by Friction Stir Welding.

Anton Naumov,Anatoly Popovich,Oleg Panchenko,Pavel Polyakov,Evgenii Rylkov,Jong-Ning Aoh,Andrey Rudskoy,Fedor Isupov

doi:10.3390/ma14216296

Anton Naumov, Anatoly Popovich + Show 6 more

Open Access

https://doi.org/10.3390/ma14216296

Copy DOI

Abstract

Friction Stir Welding (FSW) was utilized to butt−join 2024–T4 aluminum alloy plates of 1.9 mm thickness, using tools with conical and tapered hexagonal probe profiles. The characteristic effects of FSW using tools with tapered hexagonal probe profiles include an increase in the heat input and a significant modification of material flow, which have a positive effect on the metallurgical characteristics and mechanical performance of the weld. The differences in mechanical properties were interpreted through macrostructural changes and mechanical properties of the welded joints, which were supported by numerical simulation results on temperature distribution and material flow. The material flow resulting from the tapered hexagonal probe was more complicated than that of the conical probe. If in the first case, the dynamic viscosity and strain rate are homogeneously distributed around the probe, but in the case of the tapered hexagonal probe tool, the zones with maximum values of strain rates and minimum values of dynamic viscosity are located along the six tapered edges of the probe.

Highlights

The continuous thin zigzag line in the weld center extending from the top surface to the bottom was revealed in the etched macrographs of both of the examined samples, Figure 6a,b
The remnant oxide layer (ROL) in the macrostructure of the sample welded with the conical probe (Figure 6a) exhibits different features in contrast to that welded with the tapered hexagonal probe (Figure 6b)
In the case of using the conical probe, ROL passes through the top to the bottom of the entire nugget zone and reveals a curved long loop toward the retreating side (RS) in the lower part of the joint

Summary

Introduction

The range of applications is limited by the comparatively low corrosion resistance and weldability. Since Al–Cu alloys contain more alloying elements and impurities, the types of intermetallic phases formed in the alloys are likely to be the most diverse among aluminum alloys. Dispersion hardening of Al–Cu alloys occurs due to the precipitation from the solid solution and growth of the equilibrium θ−phase Al2 Cu, as well as intermediate phases and clusters. By adding Mg and Mn to the Al–Cu alloys to increase their strength [5], a hardening effect is achieved due to the precipitation and growth of more complex intermetallic phases. Depending on the ratio of the Cu and Mg concentrations, different equilibrium phases may be produced. The last−mentioned ratio of Cu:Mg is applicable to the Al–Cu–Mg alloy AA 2024.

Objectives

Methods

Results

Conclusion