The potential adaptation of stationary shoulder friction stir welding technology to steel

Maltin, Charles and Nolton, Lauren J. and Scott, Jamie L. and Toumpis, Athanasios I. and Galloway, Alexander M. (2014) The potential adaptation of stationary shoulder friction stir welding technology to steel. Materials and Design, 64. pp. 614-624. ISSN 0261-3069 (https://doi.org/10.1016/j.matdes.2014.08.017)

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Abstract

Stationary shoulder friction stir welding is a newly developed technique currently used for joining plates of relatively soft metals at different angular planes. Although the process is not currently applicable to steel, a study to investigate the theoretical and technical viability of stationary shoulder technology in DH36 steel has been undertaken. Aluminium welds were produced using both conventional rotating shoulder and stationary shoulder friction stir welding techniques, whereas steel welds were produced using only conventional friction stir welding techniques. The effects of stationary shoulder technology on both the microstructural evolution and resultant mechanical properties of aluminium have been evaluated so that the likely effects on steel could be predicted. In the aluminium welds, the stationary shoulder technique results in a distinct transition between stirred and unstirred material, in contrast to the gradual change typically seen in conventional friction stir welds produced with a rotating shoulder. An investigation of weld properties produced in DH36 steel has demonstrated that the microstructure likely to be formed, if the stationary shoulder weld technique was used, would be dominated by a bainitic ferrite phase and so would exhibit hardness and tensile properties in excess of the parent material. It is predicted that if the same abrupt transition between unstirred and stirred material, as seen in aluminium, occurred in steel this would lead to crack initiation followed by rapid propagation through the relatively brittle weld microstructure. Hence the findings demonstrate that stationary shoulder friction stir welding is unlikely to be applicable to steel without further design and process developments.

ORCID iDs

Maltin, Charles, Nolton, Lauren J., Scott, Jamie L., Toumpis, Athanasios I. ORCID logoORCID: https://orcid.org/0000-0003-3245-4536 and Galloway, Alexander M. ORCID logoORCID: https://orcid.org/0000-0003-0143-8314;
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