Abstract

The friction stir welding tool with convex pin tip was designed to realize the lap joining of 6082-T6 aluminum alloy and Q235A steel. With decreasing welding speed and increasing rotation speed, the basic constitutions of mixed stir zone changed from α-Fe fine grains, thin intermetallic compound (IMC) and Al/Fe composite structure to hook-like and chaotic mixed layered structure, resulting in joint deterioration. The maximum shear load can reach 7500 N and is predominately affected by the morphology of the IMC layers, which in turn depend on rotation speed, welding speed and other parameters. Nano-hardness decreases from about 3.9 GPa in the upper steel surface layer to about 1.3 GPa in the steel base material. Microhardness profile reveals that the maximum hardness occurs at the interface zone. The morphology of layered structure, FeAl3 IMC thickness and steel grain size can be controlled by choosing suitable welding parameters and tool shape.

Highlights

  • The application of light-weight materials allows the reduction of weight and fuel consumption in automotive and aerospace industries [1,2,3]

  • The present article investigates the interfacial characterization of friction stir lap welding (FSLW) joints of 6082-T6 aluminum alloy and Q235A steel, provides welding variable window for sound welds, and studies mechanical properties

  • This phenomenon became gradually minimized and the saw-tooth like interface produced by steel fragments gradually disappeared with increasing welding speed or decreasing rotation speed

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Summary

Introduction

The application of light-weight materials allows the reduction of weight and fuel consumption in automotive and aerospace industries [1,2,3]. Liu et al [11] analyzed effects of welding parameters on FSW joints of dissimilar aluminum alloy to advanced high strength steel and achieved sound joint which had high quality. The effects of welding speed, plunge depth, tilt angle and tool pin geometry on the IMCs and tunnel formation, and tensile strength of joints were investigated. Studied effects of welding parameters on FSW joints of 6061-T651 aluminum alloy to SS400 steel and indicated that rotation and welding speed were relatively significant process parameters compared to the tool tilt angle and pin diameter. The present article investigates the interfacial characterization of FSLW joints of 6082-T6 aluminum alloy and Q235A steel, provides welding variable window for sound welds, and studies mechanical properties. The paper investigates the interfacial structure from a metallurgical point of view

Experimental Procedure
Macrostructure of Lap Joint
Microstructure of Lap Joint
Detailed Interfacial Macro- and Microstructure
Mechanical Properties of Lap Joint
Conclusions
Full Text
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