Abstract Scope |
Friction stir welding (FSW) has been proven to be an excellent solid-state joining technology that generates robust and defect-free weldments in various grades of engineering alloys, especially in these challenging to weld using conventional fusion joining methods. However, the demand for a high spindle torque and forging loads restricts the application of FSW for thick section structural materials. Another limitation in adapting FSW is the premature tool failure when stirring high strength materials with a high melting point. In this study, induction heating assisted FSW (IHA-FSW), as a hybrid system, is developed and investigated to meet these challenges. The induction preheating assists to reduce the demand for plunging and frictional force to plasticize the material during FSW, and thus improves the efficiency and robustness of FSW and significantly extends the tool life. This hybrid system is specifically designed for an AI-enabled robot for automated nondestructive evaluation and repair of power plant boilers. The IHA-FSW process parameters were optimized based on a combination of numerical analysis and experimental measurements including recording of thermal and vertical-force profiles, profilometry analysis, and metallurgical characterizations on a test sheet low carbon steel. Hardness analysis showed that IHA-FSW produced a stir zone with matching strength to the base metal.
Keywords: Friction stir welding, low carbon steel, induction preheating, repair |