Friction stir welding in stainless steel sheet of type 430 using Ni-based dual two-phase intermetallic alloy tool

Abstract

Ferritic stainless steel SUS430 sheets were friction stir welded by using a Ni-base dual two-phase intermetallic alloy tool. After friction stir welding (FSW), the SUS430 work and the tools were evaluated in terms of microstructure and mechanical properties. The tensile specimens cut from the welded joints fractured in the base metal portion and their fracture strength was equal to that of the base metal. The stir zone comprised of recrystallized fine microstructure was observed, and also the thermo-mechanically affected zone was observed in an advanced side. Hardness in the upper one-third layer of the welded cross section was higher than the base metal. The admixture matter from work to tool surface occurred whereas that from tool to work surface did not take place in the scanning electron microscopy-EPMA resolution level. The amount of wear of tool was negligibly small, suggesting that the Ni-base dual two-phase intermetallic alloy is promising as a new type of FSW tool used for high melting materials such as steel.

Keywords:

• friction stir welding
• 430 ferritic stainless steel
• Ni-based dual two-phase intermetallic alloy
• microstructure
• mechanical property

Acknowledgements

We should like to record our gratitude for the financial assistance for part of this study provided by Basic Research (S) 21226016, Scientific Research Fund, Ministry of Education, Culture, Sports, Science and Technology.