Abstract
In this study, under the conditions of using tools at a high rotational speed (HRS) of 10,000 rpm and an ultra-high rotational speed (ultra-HRS) of 18,000 rpm, the produced welding heat input was utilized to weld two specimens of Al alloy 6061-T6 with 1.0 mm thickness and 316L SS with 0.8 mm thickness. The microstructural characteristics, mechanical properties, and electrochemical corrosion properties of the aluminum alloy–steel joints were analyzed. The higher tool offset forms an intermetallic compound layer of less than 1 µm at the Fe-Al interface on the advancing side (AS) at different speeds. This results in a mixed zone structure. The lower tool offset forms intermetallic compounds of only 2 µm. The formation of a composite material based on aluminum alloy in the weld nugget zone improves the hardness value. The intermetallic compounds are Fe3Al and FeAl3, respectively. It was observed that the formation of intermetallic compounds is solely related to the rotational speed, and the iron-rich intermetallic compounds produced under ultra-HRS parameters have higher corrosion resistance. When the tool offset is 0.55 mm, using the HRS parameters, the tensile strength is 220.8 MPa (about 75.9% of that of the base metal).
Highlights
To move beyond the “carbon peak”, as recently proposed by the Chinese government, there has been an increased demand to meet the lightweight requirements of the automobile, rail transit, and shipbuilding industries
A better lightweight alternative is the use of Al alloy with stainless steel [4] connections
The welding heat input leads to the mutual diffusion of aluminum and iron to form intermetallic compounds (IMC)
Summary
To move beyond the “carbon peak”, as recently proposed by the Chinese government, there has been an increased demand to meet the lightweight requirements of the automobile, rail transit, and shipbuilding industries. These industries widely use certain thin-plate materials. The highly economical, lightweight 6××× series Al alloy, offering superior corrosion resistance, has often been used in various applications [5,6,7]. The combination of the above two materials has attracted widespread attention in various application fields [11,12,13,14,15], such as the new energy vehicle frames, the connection of tailor-welded blanks, sealing covers, and other thin-walled structures
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