Svetskommissionen är en teknisk branschorganisation för fogande industri. Vi jobbar med standardisering, forskning och utbildning. Svetskommissionens viktigaste uppgift är att verka för våra medlemmars intressen.
Johan Löthman and Per Brännström
The three processes SuperPulse, CMT and coldArc are new techniques to utilise the MIG/MAG method. The objectives with the processes are to minimise heat-input and by increased parameter control minimise spatter and increase arc stability.
In this study the SuperPulse process is investigated for thin sheet and intermediate thickness materials. The CMT process is compared with SuperPulse and coldArc for welding of thin sheet materials, and is evaluated for joining of coated and mixed materials. The materials in the thin sheet study were DOCOL 1000 DP, HyTens 1200 and AA1050. In the intermediate plate material thickness study the selected materials were DOMEX 700 MC, 3Cr12 and SANDVIK SAF2906. For the mixed materials study the combinations of aluminium joined to zinc coated C-Mn steel and to stainless steel were selected. Coated materials were joined with welding and arcbrazing. The selected coatings were zinc in thicknesses 7-20 μm for mild C-Mn steels and AlSi of about 25 μm for press hardened C-Mn steel.
For the welding of thin sheet materials, the SuperPulse and the CMT allowed a reduction of heat-input for the selected applications in C-Mn steel stainless steel in comparison to conventional MIG/MAG welding. This was also observed for the CMT processes during welding of the aluminium application.
In intermediate plate thicknesses a reduction of heat-input with the SuperPulse process compared to conventional MIG/MAG welding was observed for the 3Cr12 steel application. The DOMEX 700 MC and SANDVIK SAF2906 could be welded with higher process stability, lower heat-input and deeper penetration compared to the conventional MAG welding. An impact toughness of 40 J/cm2 at -40°C could be reached with single-pass welding of 6 mm DOMEX 700 MC. The CMT process could braze up to 20 μm zinc coated thin sheet C-Mn steel lap joints with low amounts of porosity, low levels of spatter and high process stability. For some filler materials occurrence of liquid metal embrittlement cracking was observed.