Jukka-Pekka Anttonen, Erik Tolf, Joakim Hedegård

Abstract

In this project, welding and brazing trials of steel and aluminium joints have been performed with: Plasmatron (a constricted TIG process), plasma MIG-hybrid and with conventional plasma processes. Reference welding trials were performed with CMT. A literature survey of the plasma arc welding and brazing process is reported as a separate report with the title “Literature Survey: Plasma Welding and Brazing" (Report No.: KIMAB-2008-117). The base materials consisted of uncoated, Zn coated and AlSi coated high strength steels such as DOMEX 700, TRIP 700, DP600, DPX 1000 and USIBOR 1500P. Trials on aluminium were made with 6063 grade. Both brazing and welding of lap fillet and square butt joints were tested. The welded and brazed specimen were evaluated by x-ray examination, tensile testing and by macroscopical examination. The joint characteristics and the travel speed during welding and brazing were compared. High welding speeds with good process stability were achieved with a Plasma-MIG hybrid process for both welding and brazing, with exception for aluminium. DC plasma and Plasmatron brazing was successful. Good static strengths were achieved. Plasma welding in coated steels was however unsuccessful due to contamination of the electrode. Also aluminium welding was unsuccessful due to lack of oxide breakup. Trials with variable polarity on aluminium could unfortunately not be performed. In all, interesting benefits have been identified compared to CMT reference trials:

• Plasma and Plasmatron: extremely good visible brazed seams
• Super MIG: high productivity for both welding and brazing

More research is recommended for: Super MIG, DC+ and VPPA plasma..