Microstructure and mechanical properties of S45C steel prepared by laser-assisted friction stir welding

• Published in: Materials in engineering 2013-05, Vol.47, p.842-849
• Main Authors: Sun, Y.F., Konishi, Y., Kamai, M., Fujii, H.
• Format: Article
• Language: English
• Subjects: Carbon steel; Friction stir welding; Heating; Laser; Laser beam welding; Mechanical properties; Microstructure; Preheating; Welding; Workpieces
• ISSN: 0261-3069
• DOI: 10.1016/j.matdes.2012.12.078

► Laser can be used as extra heat source to the friction stir welding process. ► The welding speed of S45C steel can be greatly increased by laser preheating. ► The formation of martensite phase can be prevented by laser preheating. ► The position of laser beam produces different preheating effect on the welds. In this study, a laser heating system was used as a preheating source during the friction stir welding of 3.2mm thick S45C steel plates. The position of the laser focal point exerted a different preheating effect on the microstructure and mechanical properties of the welds. When the laser beam was focused just at the joint line and 10mm ahead of the rotating tool, the maximum welding speed can reach 800mm/min, which is much higher than that of 400mm/min during the normal FSW process. In addition, the formation of a brittle martensite phase can also be prevented by preheating when the welding speed is less than 600mm/min. It was also found that preheating on the advancing side can significantly reduce the frictional heat between the tool and the workpiece. However, preheating on the retreating side can result in highest total heat input into the workpiece.