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WOS: 000452499400011, The aim of this work is to investigate the mechanical properties and microstructures of friction-stir welded (FSWed) St52 structural steel joints. In this study, St52 steel plates with a thickness of 4 mm were butt-welded by friction-stir welding (FSW) using a tungsten carbide tool having a conical pin. The microstructure of the welded zone consists of equiaxed fine ferrite, grain boundary ferrite, Widmanstatten ferrite, and aggregates of ferrite + cementite. The microhardness measurements showed that the hardness of the welded zone was significantly higher than that of the base metal. The FSWed St52 joint exhibited a significant strength overmatching in the weld region and a strength performance similar to or slightly higher than that of the base plate.

WOS: 000404132100032, The mass saving potential of light-weight materials, such as Al alloys, is beneficial for fuel economy and reducing CO2 emissions. However, the wide-spread use of these alloys has been long hindered due to the difficulty in fusion joining as well as their high cost. Welding of Al alloys, which are considered to be difficult to weld through conventional arc welding, is now possible by either of low heat input arc welding, high-power density fusion joining, such as laser beam welding and electron beam welding, or friction stir welding. Particularly, friction stir welding can be successfully applied to these materials owing to the fact that no melting takes place in the weld nugget. The aim of this overview is to summarize the developments in the joining of Al alloys over the recent years. This study is also intended to provide guidance for the industry and researchers dealing with joining of these alloys.

WOS: 000372307800037, In this study, the applicability of friction stir welding to cast NAB alloy (i.e., C95800) with a thickness of 9 mm has been investigated. The joint performance was determined by conducting optical microscopy, microhardness measurements, and mechanical testing (e.g., tensile and Charpy impact tests). The effect of stir intensity on joint performance was also determined. A grain refinement (equiaxed fine grain structure) as well as evolution of a Widmanstatten structure was achieved within the stir zone of all the joints produced. Thus, all of the joints produced exhibited higher proof stress (i.e., between 512 and 616 MPa) than that of the base material, i.e., 397 MPa. On the other hand, only half of the specimens exhibited higher tensile strength values than that of the base plate (i.e., 794 MPa), whereas the other specimens displayed lower tensile strength than the base plate due to the existence of weld defects, namely cold bonding and/or tunnel defect.