Experimental review of metallurgical flash weld defects in welded joints: essence of flat spots, penetrators and oxide inclusions

Abstract

Typical flash weld defects are divided into metallurgical and mechanical defects. The metallurgical defects, which also include defects known as flat spots, penetrators and oxide inclusions, are difficult problems and develop during flashing action. The appearances and differences of flat spots, penetrators and simple oxide inclusions in flash welds are determined in this study based on literature review and experimental studies with three different steel grades. It was concluded on the basis of experimental studies that the chemical compositions of flat spots and oxide inclusions are the same, and the main difference between them is their appearance: flat spots are fracture surfaces nucleated from oxide inclusions, but simple oxide containing slags can appear also in non-fractured surfaces.

Keywords:

• Flash welding
• Flash butt welding
• Flat spot
• Penetrator
• Oxide inclusion

The authors wish to acknowledge the Finnish Funding Agency for Technology and Innovation for partial funding of this research work and the staff of Ovako Wire Oy Ab, Taalintehdas, rolling mill for providing facilities and support for experimental studies. Special acknowledges are given for LicSc A. Järvinen and MSc Techn. J. Salo for theoretical support and guidance during this research work.