Paul Janiak

Abstract

This report is based on investigations made in the SK-financed project resistance seam welding of UHSS – part 1. A continuation of this project has been financed and is scheduled to start within the membership program during 2011.

Resistance seam welding is conventionally used for welding of gas tanks, filters and water tanks which are traditionally made of stainless or mild steel. The aim of this project is to investigate resistance seam welding of ultra high strength steels (UHSS) in applications with very different demands compared to traditionally seam welded applications.

Weldability of several different UHSS material combinations has been investigated and weldability lobes were made according to SS-EN-ISO 14327 for each material combination.

Results showed that uncoated UHSS can be readily welded with only minor damage to weld electrode wheels even at high currents. Zn and AlSi coated materials however showed weldability issues. In some cases Zn-coating caused cracking of the material surface during welding. Zn also heavily damaged the electrode wheels during welding which had to be counted by using continuous wheel dressing. Limitation in equipment such as dressing units and ways to adjust to contact area of the electrode wheels is one issue that has to be countered in order to repeatedly produce high quality welds.