Influence of the weld thermal cycle on the grain structure of friction-stir joined 6061 aluminum alloy

AbstractThe main aim of this investigation is to produce a welding joint of higher strength than that of base metals. Composite welded joints were produced by friction stir welding process. 6061 aluminum alloy was used as a base metal and alumina particles added to welding zone to form metal matrix composites. The volume fraction of alumina particles incorporated in this study were 2, 4, 6, 8 and 10 vol% were added on both sides of welding line. Also, the alumina particles were pre-mixed with magnesium particles prior being added to the welding zone. Magnesium particles were used to enhance the bonding between the alumina particles and the matrix of 6061 aluminum alloy. Friction stir welded joints containing alumina particles were successfully obtained and it was observed that the strength of these joints was better than that of base metal. Experimental results showed that incorporating volume fraction of alumina particles up to 6 vol% into the welding zone led to higher strength of the composite welded joints as compared to plain welded joints.

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Characterization o Solid-State Vortices Associated with the Friction-Stir Welding of Copper to Aluminum

Microscopy and Microanalysis ◽

10.1017/s1431927600022777 ◽

1998 ◽

Vol 4 (S2) ◽

pp. 530-531

Author(s):

R. D. Flores ◽

L. E. Murr ◽

E. A. Trillo

Keyword(s):

Plastic Deformation ◽

Aluminum Alloy ◽

Friction Stir Welding ◽

Solid State ◽

Weld Zone ◽

Thick Plates ◽

6061 Aluminum Alloy ◽

Friction Stir ◽

The Past ◽

Joining Process

Although friction-stir welding has been developing as a viable industrial joining process over the past decade, only little attention has been given to the elucidation of associated microstructures. We have recently produced welds of copper to 6061 aluminum alloy using the technique illustrated in Fig. 1. In this process, a steel tool rod (0.6 cm diameter) or head-pin (HP) traverses the seam of 0.64 cm thick plates of copper butted against 6061-T6 aluminum at a rate (T in Fig. 1) of 1 mm/s; and rotating at a speed (R in Fig. 1) of 650 rpm (Fig. 1). A rather remarkable welding of these two materials results at temperatures measured to be around 400°C for 6061-T6 aluminum welded to itself. Consequently, the metals are stirred into one another by extreme plastic deformation which universally seems to involve dynamic recrystallization in the actual weld zone. There is no melting.

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Microstructure Evolution and Mechanical Property Characterization of 6063 Aluminum Alloy Tubes Processed with Friction Stir Back Extrusion

JOM ◽

10.1007/s11837-019-03852-7 ◽

2019 ◽

Vol 71 (12) ◽

pp. 4436-4444

Author(s):

Suhong Zhang ◽

Alan Frederick ◽

Yiyu Wang ◽

Mike Eller ◽

Paul McGinn ◽

...

Keyword(s):

Aluminum Alloy ◽

Microstructure Evolution ◽

Electron Backscatter Diffraction ◽

Deformation Gradient ◽

Optical Microscope ◽

Grain Structure ◽

Frictional Heat ◽

Friction Stir ◽

Metal Extrusion ◽

Backscatter Diffraction

Abstract Friction stir back extrusion (FSBE) is a technique for lightweight metal extrusion. The frictional heat and severe plastic deformation of the process generate an equiaxed refined grain structure because of dynamic recrystallization. Previous studies proved that the fabrication of tube and wire structures is feasible. In this work, hollow cylindrical billets of 6063-T6 aluminum alloy were used as starting material. A relatively low extrusion ratio allows for a temperature and deformation gradient through the tube wall thickness to elucidate the effect of heat and temperature on the microstructure evolution during FSBE. The force and temperature were recorded during the processes. The microstructures of the extruded tubes were characterized using an optical microscope, energy-dispersive x-ray spectroscopy, electron backscatter diffraction, and hardness testing. The process reduced the grain size from 58.2 μm to 20.6 μm at the inner wall. The microhardness of the alloy was reduced from 100 to 60–75 HV because of the process thermal cycle.

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